There are remarkable developments now in quantum computation, and it is time to expose the scientific public to down-to-earth explanations... We are happy to announce a series of monthly afternoon semi-public lectures (for a wide audience of CS and Physics), given by top-world quantum experts, from both CS and Physics, called QUANTUM SCIENCE PERSPECTIVES, and intended also for NON-QUANTUM experts. The lectures will be given by top notch world leading researchers, and will alternate between more CS or more Physics perspectives.

Note: each such event will be followed by a reception, nice food and beverages, and intermingling, and preceded by a one hour basic informal preparation talk (mostly for students but everyone is welcome!), to help provide some background for the talk (these prep talks will not be assumed in the main lectures - these will be self contained).

The first talk of the year, will be given by Prof. Aephraim Steinberg from The University of Toronto. The talk will focus on the question of the time a particle takes to tunnel through a classically forbidden region.

Everyone is welcome!!!

Please see www.quantumperspectives.org for more info and RSVP.

(Please note: The program starts at 4pm. Food and beverages will be served after the talks at 6pm)

This next talk, will be given by Prof. Scott Aaronson from The University of Texas at Austin, in Levine hall. The talk will focus on the possibility of efficiently solving NP-complete problems using resources of the physical world.

Everyone is welcome!!!

Please see www.quantumperspectives.org for more info.

It would be great if you spend the ten seconds required to press on the RSVP there to say you are coming, for food issues, but not necessary. Also, there is a place to put your name there so that you get emails about the future lectures.

Looking forward seeing you!

(Please note: The program starts at 4pm. Food and beverages will be served after the talks at 6pm)

Please see www.quantumperspectives.org for more info

• 9:30-10:00 Breakfast and Coffee
• 10:00-10:15 Greetings
  Barak Medina - Rector
  Hagai Netzer - Wolf foundation
  Michael Ben Or
• 10:15-11:35 Plenary Session
• 10:15-10:55 Charles Bennett
  "Occam’s razor, Boltzmann’s brain and Wigner’s friend: reconciling reversible dynamics with human experience"
• 10:55-11:35 Gilles Brassard
  "All no-signaling theories are local-realistic"
• 11:35-12:00 Coffee Break
• 12:00-12:50 Session I
• 12:00-12:25 Dorit Aharonov
  "Philosophical questions with computational answers"
• 12:25-12:50 Yaron Silberberg
  "Quantum Microscopy"
• 12:50-13:50 Lunch
• 13:50-14:40 Session II
• 13:50-14:15 John Smolin
  "The Early Days of Quantum Cryptography"
• 14:15-14:40 Eleni Diamanti
  "Towards Quantum Cryptography for All"
• 14:40-15:10 Coffee Break
• 15:10-16:00 Session III
• 15:10-15:35 Scott Aaronson
  "Certified Randomness from Quantum Supremacy"
• 15:35-16:00 John Howell
  "Spooky Action in High Dimensions"
• 16:00 Farewell

For more details quantum.huji.ac.il/BB2018

For registration please click here

This unique interdisciplinary workshop brings together leading international experts, both theorists and experimentalists, on quantum dipolar gases, as well as young researchers and students from two communities: atomic physics and condensed-matter physics. The workshop will stimulate the exchange of ideas around this topic and thus create a framework for new collaborations in this interdisciplinary field of research. Initiating and motivating exchange of knowledge and ideas between the two communities to combine these complementary know-hows would hopefully lead to new and original research directions.

The school will cover the following topics:

• Magnetic dipolar atomic gases
• Dipolar Rydberg atoms/polaritons
• Ultracold polar molecules
• Dipolar excitons (including Rydberg excitons)
• Dipolar Exciton-polaritons
• Dipolar Excitons in bilayers of 2D electron gases, graphene, and emerging 2D materials

The study of many-body quantum states of matter in cold dipolar systems is motivated by special features of the dipolar interaction – its long range and anisotropic character. The fundamental physics questions and technological promises of these special dipolar species go well-beyond the state-of-the-art of the weakly interacting atomic gases, with important consequences for many body systems as well as for applications in quantum information and quantum simulation.

The 3-day event will take place on October 23-25th, 2017, at the Israel Institute for Advanced Studies (IIAS), within the beautiful, green, and peaceful Edmond J. Safra campus of the Hebrew University which is located in the heart of the inspiring city of Jerusalem.

The intimate event will include comprehensive lectures from established experts to cover the state-of-the art in their corresponding fields, as well as presentations from the younger scientists, to allow them to expose their work to the relevant audience. Finally, the schedule will include sufficient time for informal discussions between participants. This will be facilitated by long discussion breaks between talks together with joint meals and evening slots for poster presentations and informal discussions.

Registration for the school is now open, and we still have a slots for participants and for poster presentations.

You are invited to register through the registration page on our website, where you can find instruction for registration, abstract submission, and payment:

https://www.dip-quantum-2017.com/registration

Please note that the deadline for abstract submission is Sept. 30th.

We hope to see you soon,
The organizing committee,
Paulo Santos and Ronen Rapaport
https://www.dip-quantum-2017.com

The Hebrew University and the University of Melbourne are organizing a workshop on Diamond Architectures for Quantum Computing and Sensing, which will be held at the Mishkenot Sha'ananim conference center, between February 13-16. The scientific program, speaker list and all other relevant information can be found on the workshop website: http://www.daqcs2017.com.

"Quantum optical technologies for metrology, sensing and imaging"

Over the past 20 years, bright sources of entangled photons have led to a renaissance in quantum optical interferometry. Optical interferometry has been used to test the foundations of quantum mechanics and implement some of the novel ideas associated with quantum entanglement such as quantum teleportation, quantum cryptography, quantum lithography, quantum computing logic gates, and quantum metrology. In this paper, we focus on the new ways that have been developed to exploit quantum optical entanglement in quantum metrology to beat the shot-noise limit, which can be used, e.g., in fiber optical gyroscopes and in sensors for biological or chemical targets. We also discuss how this entanglement can be used to beat the Rayleigh diffraction limit in imaging systems such as in LIDAR and optical lithography and microscopes.

ETH Zurich and The Hebrew University will hold a joint two days workshop on quantum technologies in Jerusalem.

Sunday, November 20th (Beit Belgia)

• 18:00-19:00 Arrival, Reception and Dinner
• 19:00-19:10 Greetings – Nadav Katz and Andreas Wallraff
• 19:10-19:40 Alex Retzker, HUJI New methods for high frequency resolution measurements
• 19:40-20:10 Martin Frimmer (Novotny group), ETH Optomechanical oscillators: Coherent control and the photon recoil limit
• 20:15-22:30 Bus back to Hotel, and evening walk in Jerusalem (for whomever is interested)

Monday, November 21st (Beit Breter)

• 09:00-09:30 Introduction and greetings:
  Prof. Isaiah (Shy) Arkin, HUJI VP for R&D
  Prof. Lino Guzzella, ETH president
  Prof. Jay Fineberg, HUJI Dean of the Faculty of Sciences
  Prof. Klaus Ensslin, ETH (representative of NCCR QSIT)
  Prof. Nadav Katz, HUJI
  
• 09:30-10:00 Jonathan Home, ETH Dissipative sensing and quantum state engineering with trapped atomic ions
• 10:00-10:30 Nadav Katz, HUJI Superconducting circuits - how far are we from quantum supremacy?
• 10:30-11:00 Renato Renner, ETH True randomness from quantum devices
• 11:00-11:30 Coffee break
• 11:30-12:00 Hadar Steinberg, HUJI Tunneling spectroscopy of NbSe₂ in van-der-Waals devices
• 12:00-12:30 Klaus Ensslin, ETH Fermionic cavities and spin coherence
• 12:30-14:00 Lunch
• 14:00-16:00 Lab tours: Hagai Eisenberg, Yossi Paltiel, Nir Bar-Gill
• 16:00-16:30 Coffee break
• 16:30-17:00 Uriel Levy, HUJI Linear and nonlinear light-vapour interactions on a chip
• 17:00-17:30 Andreas Wallraff, ETH Quantum Science and Technology with Superconducting Circuits
• 17:30-18:00 Ronen Rapaport, HUJI From single-body to many-body quantum physics in semiconductor nano-structures
• 18:00-18:30 Sebastian Huber, ETH Quantum inspired engineering: The next generation mechanical metamaterials
• 18:30-20:00 Posters + light dinner and beer
• 20:00 Bus to Rehovot

The Center for Quantum Information and Quantum Control (CQIQC), located at the University of Toronto, is accepting applications for Prize Scholarships for Undergraduate Students to undertake Summer Research Projects at the University of Toronto in 2016. CQIQC will provide funds for students to spend the summer working in one of the research groups associated with the Center.

Application information
CQIQC

Einstein is well known for his rejection of quantum mechanics in the form it emerged from the work of Heisenberg, Born and Schrodinger in 1926. Much less appreciated are the many seminal contributions he made to quantum theory prior to his final scientific verdict, that the theory was at best incomplete. In this talk I present an overview of Einstein’s many conceptual breakthroughs and place them in historical context. I argue that Einstein, much more than Planck, introduced the concept of quantization of energy in atomic mechanics. Einstein proposed the photon, the first force-carrying particle discovered for a fundamental interaction, and put forward the notion of wave-particle duality, based on sound statistical arguments 14 years before De Broglie’s work. He was the first to recognize the intrinsic randomness in atomic processes, and introduced the notion of transition probabilities, embodied in the A and B coefficients for atomic emission and absorption. He also preceded Born in suggesting the interpretation of wave fields as probability densities for particles, photons, in the case of the electromagnetic field. Finally, stimulated by Bose, he introduced the notion of indistinguishable particles in the quantum sense and derived the condensed phase of bosons, which is one of the fundamental states of matter at low temperatures. His work on quantum statistics in turn directly stimulated Schrodinger towards his discovery of the wave equation of quantum mechanics. It was only due to his rejection of the final theory that he is not generally recognized as the most central figure in this historic achievement of human civilization.

"Schrödinger’s Rainbow: The Renaissance in Quantum Optical Interferometry"

Over the past 20 years bright sources of entangled photons have lead to a renaissance in quantum optical interferometry. These photon sources have been used to test the foundations of quantum mechanics and implement some of the spooky ideas associated with quantum entanglement such as quantum teleportation, quantum cryptography, quantum lithography, quantum computing logic gates, and sub-shot-noise optical interferometers​. I will discuss some of these advances and the unification of optical quantum imaging, metrology, and information processing.

"Linear Optical Quantum Metrology with Single Photons: Exploiting Spontaneously Generated Entanglement to Beat the Shot-Noise Limit"

Quantum number-path entanglement is a resource for super-sensitive quantum metrology and in particular provides for sub-shot noise or even Heisenberg-limi​ted sensitivity. However, such number-path entanglement has thought to have been resource intensive to create in the first place --- typically requiring either very strong nonlinearities, or nondeterministi​c preparation schemes with feed-forward, which are difficult to implement. Very recently, arising from the study of quantum random walks with multi-photon walkers, as well as the study of the computational complexity of passive linear optical interferometers fed with single-photon inputs, it has been shown that such passive linear optical devices generate a super-exponenti​ally large amount of number-path entanglement. A logical question to ask is whether this entanglement may be exploited for quantum metrology. We answer that question here in the affirmative by showing that a simple, passive, linear-optical interferometer --- fed with only uncorrelated, single-photon inputs, coupled with simple, single-mode, disjoint photo-detection --- is capable of significantly beating the shot-noise limit. Our result implies a pathway forward to practical quantum metrology with readily available technology.

"Inefficiency of classically simulating linear optical quantum computing with Fock-state inputs"

Aaronson and Arkhipov recently used computational complexity theory to argue that classical computers very likely cannot efficiently simulate linear, multimode, quantum-optical interferometers with arbitrary Fock-state inputs [Aaronson and Arkhipov, Theory Comput. 9, 143 (2013)]. Here we present an elementary argument that utilizes only techniques from quantum optics. We explicitly construct the Hilbert space for such an interferometer and show that its dimension scales exponentially with all the physical resources We also show in a simple example just how the Schrödinger and Heisenberg pictures of quantum theory, while mathematically equivalent, are not in general computationally equivalent. We conclude our argument by comparing the symmetry requirements of multiparticle bosonic to fermionic interferometers and, using simple physical reasoning, connect the nonsimulatabili​ty of the bosonic device to the complexit of computing the permanent of a large matrix. Finally we discuss our recent work on time-binned Boson Sampling and Boson Sampling with nonclassical states of light other than Fock states, such as Schrödinger-cat states, photon-added or -subtracted squeezed states, and photon-added coherent states.

In recent years, several studies have indicated that "non-trivial" quantum features such as superposition, nonlocality, entanglement and tunneling may be manifested in a number of biological processes. These findings give rise to a new area of research: “Quantum Biology”. Some examples of the biological phenomena that have been studied in terms of quantum processes are the absorbance of frequency-specific radiation (i.e., photosynthesis and vision); the conversion of chemical energy into motion; magnetoreception in animals, DNA mutation, and brownian motors in many cellular processes. The research of quantum biology is still at its fledgling phase, and its essence is under intense debate. However, it bears the potential to be of paramount importance for the understanding of biological phenomena at the fundamental level, and may induce in the future the physical chassis for implementing quantum computing concept The sixth Peter Brojde Conference at explore recent development in this field.

Free registration here

Registration for free transportation from HUJI here

The conference schedule:

• 08:45-09:15 Registration
• 09:15-09:30 Welcome
• 09:30-10:15 Prof. Martin Plenio, Ulm University “Quanta, Vibrations and Biology”
• 10:15-10:45 Prof. Yossi Paltiel, The Hebrew University of Jerusalem “Quantum Random Walk in Biological Phycocyanin Nanowires”
• 10:45-11:15 Coffee break
• 11:15-11:45 Ms. Nirit Kantor-Uriel, The Weizman Institute of Science “How to measure spin polarization in electron transfer through bio systems?”
• 11:45-12:15 Prof. Ronnie Kosloff, The Hebrew University of Jerusalem
• 12:15-12:45 Prof. Nir Keren, The Hebrew University of Jerusalem “An easily reversible structural change underlies mechanisms enabling desert crust cyanobacteria to survive desiccation”
• 12:45-14:00 Lunch
• 14:00-14:30 Prof. Noam Adir, Technion-Israel Institute of Technology “Does the structure of the Phycobilisome photosynthetic antenna complex help decipher its energy transfer properties?”
• 14:30-15:15 Prof. Richard Cogdell, University of Glasgow “How ‘strange’ is photosynthetic light harvesting?”
• 15:15-15:30 Prof. Ronny Agranat, The Hebrew University of Jerusalem Concluding Remarks

While we understand well how two classical dipoles interact with each other, the problem becomes much more complex and interesting when we put many dipoles together and form a dipolar fluid, especially when collective quantum effects become important. A dipolar exciton fluid in a semiconductor bilayer is a wonderful system to look for the very rich quantum-collective physics that is theoretically predicted for ultra-cold dipoles. Furthermore, these exciton fluids can be utilized for new types of circuitry on a chip.

I will give an overview of the recent research highlights on dipolar exciton fluids, with many new exciting observations such as a transition from a classical to a quantum correlated fluid, evidences for a macroscopic formation of an incompressible dark liquid, as well as observations of very long spin lifetimes. I will also present some proof-of-principle experiments of building blocks for a complex excitonic circuitry and of the ability to form dipolar molecules with out-of-plane interactions.

The Hebrew University Optical Society of America (OSA) chapter is hosting a special event within the announced International Year of Light (2015). The event's goal is to present the HUJI chapter's activities and ambitions by exposing them to a wider audience.

The event will feature talks by Prof. Hagai Eisenberg (HUJI) and Dr. Eyal Shekel (CEO, Sivan). To conclude, refreshments and more will be served. The full itinerary:

• 15:00 - 15:15 Gathering and light refreshments
• 15:15 - 15:30 Introduction and presentation of the HUJI OSA chapter
• 15:30 - 16:30 Academia talk: "Quantum Computation Using Entangled Photons", Prof. Hagai Eisenberg, The Hebrew University
• 16:30 - 17:00 Recess, light refreshments
• 17:00 - 18:00 Industry talk: "High Power Laser Assembly with Coherent Addition of Semi-Conductor Optical Amplifiers", Dr. Eyal Shekel, Sivan CEO (Jerusalem)
• 18:00 - 19:00 Conclusion and refreshments

Please be advised that (free) registration is required.

Electric and magnetic dipolar interactions between atoms are ubiquitous. In many cases they are responsible for the formation of molecules, the emergence of magnetism, as well as many other physical phenomena. Usually these interactions decay as the cube of the distance between atoms and are therefore dominant only on atomic scale separations between atoms. Here I’ll describe the measurement of dipolar interactions between atomic ions that are separated by several micrometers in trapped-ion crystals. I’ll describe the measurement of the magnetic dipolar interaction between the two valence electrons of two ions as well as the collective Lamb-shift which arises from resonant electric dipole interaction between ions.

[1] Measurement of the magnetic interaction between two bound electrons of two separate ions, Shlomi Kotler, Nitzan Akerman, Nir Navon, Yinnon Glickman, Roee Ozeri, Nature 510, 376 (2014)
[2] Cooperative Lamb shift in a mesoscopic atomic array, Ziv Meir, Osip Schwartz, Ephraim Shahmoon, Dan Oron, Roee Ozeri, Phys. Rev. Lett. 113, 193002 (2014)

An APS quantum computing workshop will take place on Tuesday, January 6^th, for the general audience.
In the program:

• 16.00 - 16.10 Prof. M. Ya. Amusia "Introductory remarks"
• 16.10 - 17.00 Prof. G. Kalai "What can we learn from a failure of quantum computers"
• 17.00 - 17.50 Prof. N. Katz "Quantum information science - the state of the art"
• 17.50 - 18.15 General discussion

All interested, including students, are welcomed.
Refreshments will be served in the lobby of Danciger B building, from 15.45.

Twenty years after the discovery of Shor's factoring algorithm, I'll survey what we now understand about the structure of problems that admit quantum speedups. I'll start with the basics, discussing the hidden subgroup, amplitude amplification, adiabatic, and linear systems paradigms for quantum algorithms. Then I'll move on to some general results, obtained by Andris Ambainis and myself over the last few years, about quantum speedups in the black-box model. These results include the impossibility of a superpolynomial quantum speedup for any problem with permutation symmetry, and the largest possible separation between classical and quantum query complexities for any problem.

Several members of QISC visited ETH Zurich, and held an exciting two-day workshop discussing possible collaboration.

In the photo (from left to right): Nadav Katz, Guy Ron, Ronen Rapaport, Nir Bar-Gill, Hadar Steinberg, Michael Ben-Or, Andreas Wallraff and Jerome Faist. Click here for the program of the workshop

Solid state transistors triggered a revolution in the way we store, compute and communicate information. Half a century after this revolution began a new type of processing has emerged based on quantum instead of classical physics. Solid state devices based on diamond, silicon and other semiconductor systems have been proposed with spin-based quantum bits to form the backbone of the quantum processor, but to date a viable large-scale architecture remains to be demonstrated. We have used ion implantation to insert phosphorus atoms into silicon to explore quantum computer technology based on potentially scalable engineered single donor atom devices. It is now possible to fabricate nanoscale silicon transistors with a channel length (~20 nm) that is comparable in size to the Bohr orbit of the donor electrons (~1.22 nm for Si:P). Our approach is to engineer nano-scale silicon CMOS devices with a single 31P atom implanted with our deterministic doping method [1] that is cited by the International Semiconductor Roadmap for 2011 [2]. Our devices have now proved the ability to perform single shot readout of the donor electron spin [3]. We use electron spin resonance to drive Rabi oscillations to show a coherence time (T2) exceeding 200 µs suggesting a single P donor electron spin can be used as a long-lived quantum bit [4]. The same devices show P nuclear spin coherence times for ionized donors of 60 ms [5]. New devices built from enriched 28Si, described as a "semiconductor vacuum" because of the absence of decohering background spins, offer even longer coherence times. This presentation describes our approach to take this technology to the next stage by building deterministic arrays of single atoms. We seek to exploit the remarkable coincidence that the range over which it is possible to couple electrons in the solid state is comparable to the straggling range of shallow donor atoms implanted <20 nm deep into a semiconductor wafer. This presentation reviews the challenges of building a large scale quantum device for computation and communication that may ul timately lead to the quantum internet of the mid-21st C.

[1] DN Jamieson, C Yang, T Hopf, SM Hearne, CI Pakes, S Prawer, M Mitic, E Gauja, SES Andresen, FE Hudson, AS Dzurak & RG Clark, Controlled shallow single-ion implantation in silicon using an active substrate for sub-20-keV ions, Appl. Phys. Lett. 86, p202101 1-3 (2005)
[2] International Technology Roadmap for Semiconductors, Emerging Research Materials www.itrs.net/Links/2011ITRS/2011Chapters/2011ERM.pdf
[3] JJ Pla, FA Zwanenburg, KW Chan, H Huebl, M Möttönen, CD Nugroho, C Yang, JA van Donkelaar, A Alves, DN Jamieson, CC Escott, LCL Hollenberg, RG Clark & AS Dzurak, Single-shot readout of an electron spin in silicon, Nature 467 687 (2010)
[4] JJ Pla, KY Tan, JP Dehollain, WH Lim, JJL Morton, DN Jamieson, AS Dzurak & A Morello, A single-atom electron spin qubit in silicon, Nature 489 541 (2012)
[5] JJ Pla, KY Tan, JP Dehollain, WH Lim, JJL Morton, FA Zwanenburg, DN Jamieson, AS Dzurak, A Morello, A high-fidelity single nuclear spin qubit in silicon, Nature 496 334 (2013)

This research was conducted by the Australian Research Council Centre of Excellence for Quantum Computation and Communication Technology (project number CE110001027 and the US Army Research Office (grant number W911NF-08-1-0527). We acknowledge the collaborations of Changyi Yang, Andrew Alves, Jeff McCallum (University of Melbourne), Andrew Dzurak, Andrea Morello, Fay Hudson (UNSW) and Thomas Schenkel (LBNL).

Using modern micro and nano-fabrication techniques combined with superconducting materials we realize quantum electronic circuits in which we create, store, and manipulate individual microwave photons. The strong interaction of photons with superconducting quantum two-level systems allows us to probe fundamental quantum effects of microwave radiation and also to develop components for applications in quantum technology. Previously we have realized on-demand single photon sources which we have characterized using correlation function measurements [1] and full quantum state tomography [2].
For this purpose we have developed efficient methods to separate the quantum signals of interest from the noise added by the linear amplifiers used for quadrature amplitude detection [3] We now regularly employ superconducting parametric amplifiers [4] to perform nearly quantum limited detection of propagating electromagnetic fields. These enable us to probe the entanglement which we generate on demand between stationary qubits and microwave photons freely propagating down a transmission line [5]. Using two independent microwave single photon sources, we have recently performed Hong-Ou-Mandel experiments at microwave frequencies [6] and have probed the coherence of two-mode multi-photon states at the out-put of a beam-splitter. The non-local nature of such states may prove to be useful for distributing entanglement in future small-scale quantum networks.

[1] D. Bozyigit et al., Nat. Phys. 7, 154 (2011)
[2] C. Eichler et al., Phys. Rev. Lett. 106, 220503 (2011)
[3] C. Eichler et al., Phys. Rev. A 86, 032106 (2012)
[4] C. Eichler et al., Phys. Rev. Lett. 107, 113601 (2011)
[5] C. Eichler et al., Phys. Rev. Lett. 109, 240501 (2012)
[6] C. Lang et al., Nat. Phys. 9, 345–348 (2013)

Recently there has been intense interest in claims about the performance of the D-Wave machine. Scientifically the most interesting aspect was the claim based on extensive experiments, that the machine exhibits large-scale quantum behavior. This conclusion was based on the strong correlation of the input-output behavior of the D-Wave machine with a quantum model called simulated quantum annealing, in contrast to its poor correlation with two classical models: simulated annealing and classical spin dynamics. In this paper, we outline a simple new classical model, and show that on the same data it yields correlations with the D-Wave input-output behavior that are at least as good as those of simulated quantum annealing. Based on these results, we conclude that classical models for the D-Wave machine are not ruled out. Further analysis of the new model provides additional algorithmic insights into the nature of the problems being solved by the D-Wave machine.

Ion crystals for quantum computing, simulation and non-equilibrium physics?

Ion crystals are among the most controlled quantum systems. The crystal structure is controlled with high precision using the dynamic and the static Paul potentials. As an alternative to quantum computation which small linear crystals, shuttled in micro trap arrays, as pioneered by Wineland [Science 325, 1227 (2009), PRL109, 080501 (2012)] we aim for planar crystal structures, and investigate this structural transition [PRL 109, 263003 (2012)] also under non-equilibrium conditions [Nat. Comm. 4, 2290 (2013)]. Interactions for quantum magnetic simulations are mediated using laser interactions. State-dependent forces are generated with non-resonant Raman beams [NJP 14, 093042 (2012), PRL 107, 207209 (2011), PRL 108, 235701 (2012)]. A novel approach is the use of specific properties of Rydberg excitations for trapped ion crystals, we prepare a cold 40-Ca+ ion crystal, excite the S1/2 - D5/2 transition near 729nm and apply radiation near 123nm for Rydberg excitation. We report the investigation of mixed crystals of single and doubly ionized Ca, for mode design and structural configuration [arxiv 1306.1109] along the proposals [PRL 108, 023003 (2012), PRA 87, 052304 (2013)].

Lunch break

What has Bell's theorem to do with the absence of antimatter in our universe?

John Stewart Bell was known and hired as a "particle physicist" when he came up with his work on hidden parameters exactly 50 years ago. The aim of this talk is to discuss whether his theorem can be brought back to those systems that do not build up ordinary matter and light, i.e. to the domain of Particle Physics. Indeed, massive K-meson pairs are copiously produced at accelerator facilities that are entangled in their strangeness quantum number, i.e. being in the particle or antiparticle state. Entanglement and its manifestations reveal differently than in quantum systems of low energy [1]. In particular, it turned out that there exists a connection between the violation of Bell's inequality and the tiny violation of the CP symmetry (C...charge conjugation, P...parity). The broken CP symmetry, verified in various accelerator facility experiments, shows a small difference between a world of matter and a world of antimatter. This relates two different powerful toolboxes in physics, entanglement and symmetries in Particle Physics. Moreover, the discovery of CP violation, also exactly 50 years old, can be attributed to the unsolved problem why we live in a universe dominated by matter, i.e. why has antimatter disappeared? In the last part of the talk I show that these meson-antimeson systems are a unique laboratory to study foundations of quantum mechanics, e.g., for testing different kinds of quantum eraser schemes or decoherence models or collapse models [2].

[1] Hiesmayr et al., "/Revealing Bell's Nonlocality for Unstable Systems in High Energy Physics/", EPJ C, Vol. 72, 1856 (2012).
[2] Brahami et al., "/Are collapse models testable with quantum oscillating systems? The case of neutrinos, mesons, chiral molecules/", Nature: Scientific Reports 3, 1952 (2013).

How do we optimally extract precision information from continuous measurement records?

Quantum systems find use as precision probes, as well as time and frequency standards, and much research has dealt with the sensitivity of measurement schemes based on the preparation, evolution and final detection of different, particular quantum states. In this talk, I shall discuss another common scheme for precision probing, where a fluctuating signal is retrieved continuously in time, while the quantum system that emits the signal follows a stochastic evolution, sometimes referred to as a quantum trajectory. I shall show how the stochastic master equation describing the dynamics of such a quantum system effectively "filters" the likelihood functions for any unknown parameters in the system dynamics. I shall also show that the theoretical sensitivity limit for parameters that govern the system dynamics can be obtained from the (un-observed) system master equation. With detection of atomic fluorescence signals as an example, I shall demonstrate that photon counting and homodyne detection of the signal yield different sensitivity to the atomic and field parameters, while none of them exceed the general sensitivity limit.

Lunch break

Measuring Entanglement and Quantum States Efficiently

One of the principal features distinguishing classical from quantum many-body systems is that quantum systems require exponentially many parameters in the system size to fully specify the state, compared to only linearly many for classical systems. Put to use constructively, the exponential complexity enables the construction of information processing devices fundamentally superior to any classical device. At the same time, however, this "curse of dimensionality" makes engineering tasks such as verifying that the quantum processing device functions as intended -- a daunting challenge. Here I show that one can do exponentially better than direct state tomography for a wide range of quantum states, in particular those that are well approximated by a matrix product state ansatz. Furthermore, I demonstrate that the extraction of complex functions of the quantum state, such as entanglement can be achieved very efficiently if one sacrifices the desire to know exact value instead being satisfied with very good upper and lower bounds. I will present both theoretical methods and the results of experiments in which these methods have been applied.

Uncertainty relations are a distinctive characteristic of quantum theory that imposes intrinsic limitations on the precision with which physical properties can be simultaneously determined. The modern work on uncertainty relations employs entropic measures to quantify the lack of knowledge associated with measuring non-commuting observables. However, I will show here that there is no fundamental reason for using entropies as quantifiers; in fact, any functional relation that characterizes the uncertainty of the measurement outcomes can be used to define an uncertainty relation. Starting from a simple assumption that any measure of uncertainty is non-decreasing under mere relabeling of the measurement outcomes, I will show that Schur-concave functions are the most general uncertainty quantifiers. I will then introduce a novel fine-grained uncertainty relation written in terms of a majorization relation, which generates an infinite family of distinct scalar uncertainty relations via the application of arbitrary measures of uncertainty. This infinite family of uncertainty relations includes all the known entropic uncertainty relations, but is not limited to them. In this sense, the relation is universally valid and captures the essence of the uncertainty principle in quantum theory. This talk is based on a joint work with Shmuel Friedland and Vlad Gheorghiu.

The Hebrew University of Jerusalem Quantum Information Center is proud to announce its very first conference which will be held on the 24^th to the 27^th of June 2013.
This event has in store a promising entourage of highly distinguished lecturers from all around the world, offering much insight into quantum information related theories and practice, revealed through their innovative works.
For further information, details and registration please follow this link to visit the official pages of the conference.

Quantum memories: design and applications

10:00-11:00

Quantum memories are devices where one can store and retrieve quantum states. In order to preserve the states in the presence of decoherence, one may use quantum error correction techniques. An alternative approach consists of employing interacting spins so that no active action on the memory is require during the whole storage period. In this talk I will analyze the robustness of such memories against decoherence, as well as those based on dissipation, whereby an interaction of the spins with an environment is properly engineered. I will also analyze the security of protocols using quantum memories, like those related to quantum money and credit cards, as well as some experimental attempts to extend the memory time of qubits at room temperature.

Quantum Information Processing with Quantum Optical Systems

11:15-12:15

Quantum optical systems of cold atoms, molecules and ions provide one of the best ways to implement quantum information processing tasks, including quantum computing, quantum simulation and quantum communication. The talk starts with a short overview of quantum optical systems with focus on ions and cold atoms. We then discuss our recent work on "open system" quantum simulation and entangled states preparation via quantum reservoir engineering, and discuss related ion experiments. In addition, we give a summary of our present activities in simulating toy models of lattice gauge theories with cold atoms.

Band-limited functions can oscillate arbitrarily faster than their fastest Fourier component over arbitrarily long intervals. Where such "superoscillati​ons" occur, functions are exponentially weak. In typical monochromatic optical fields, substantial fractions of the domain (one-third in two dimensions) are superoscillator​y. Superoscillatio​ns have implications for signal processing, and raise the possibility of sub-wavelength resolution microscopy without evanescent waves. In quantum mechanics, superoscillatio​ns correspond to weak measurements, suggesting weak values of observables (e.g photon momenta) far outside the range represented in the quantum state. A weak measurement of neutrino speed could lead to a superluminal result without violating causality, but the effect is too small to explain the speed claimed in a recent experiment.

In contrast to entropy, which increases monotonically, the "complexity" or "interestingness" of closed systems seems intuitively to increase and then decrease: for example, our universe lacked complex structures at the Big Bang and will also lack them after it reaches thermal equilibrium. I'll discuss an initial attempt to quantify this pattern. As a model system, we use a simple, two-dimensional cellular automaton that simulates the mixing of two liquids ("coffee" and "cream"). A plausible complexity measure is then the Kolmogorov complexity of a coarse-grained approximation of the automaton's state. We study this complexity measure, and show analytically that it never becomes large when the liquid particles are non-interacting. By contrast, when the particles do interact, we give numerical evidence that the complexity reaches as a maximum comparable to the "coffee cup's" horizontal dimension. We raise the problem to prove this behavior analytically.
Joint work with Lauren Ouellette and Sean Carroll.

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One of the major open problems in quantum information concerns with the question whether entanglement between signal states can help to send classical information on quantum channels. Recently, Hasting proved that entanglement does help by finding a counter-example for the long standing additivity conjecture that the minimum von-Neumann entropy output of a quantum channel is additive under taking tensor products. In this talk I will show that the minimum von-Neumann entropy output of a quantum channel is locally additive. Hasting's counterexample for the global additivity conjecture, makes this result somewhat surprising. In particular, it indicates that the non-additivity of the minimum entropy output is related to a global effect of quantum channels. I will end with few related open problems.