One of the main obstacles preventing the realization of a quantum computer is generating the
fundamental two-body interaction gates in the presence of noise with a fidelity below the fault
tolerance threshold. This work proposes ways to overcome various noise sources in systems used for
quantum computing, and improved sensing techniques with quantum probes; First, by utilizing
(pulsed) dynamical decoupling as a tool to control two-qubit-gate dynamics – instead of restricting
the system to incorporate the pulses. Thus, gaining a fast gate that is decoupled from noise [2].
Second, by using composite pulses to refocus the building blocks of two-qubit-gates that utilize
ultrafast laser pulses [1]. In this case the pulses themselves decouple the qubits from noise and by
making use of composite pulses we also deal with laser shot-to-shot mplitude errors. Finally,
addressing the limits of frequency resolution achievable with a quantum probe [3] (e.g., in
nano-NMR experiments or when calibrating quantum computer); Super-resolution post-processing
technique for resolving two close frequencies by using an averaged maximum likelihood estimator –
such that the resolution scales as single frequency estimation. And the resolution limit obtained from
the new diffusion model proposed by Cohen et. al. for the nano-NMR scenario [4] – which presents
long lived correlations. These research fields are of course still developing, one of the leading
platforms for quantum computing is with superconducting circuits and incorporating methods for
noise suppression, and dealing with calibration error, is still an open challenge.
1. Refocusing two qubit gate noise for trapped ions by composite pulses.
I. Cohen, A. Rotem, A. Retzker. Phys. Rev.. A 93, 032340 (2016)
2. Fast Dynamical Decoupling of the Mólmer-Sórensen Entangling Gate.
T. Manovitz, A. Rotem, R. Shaniv, I. Cohen, Y. Shapira, N. Akerman, A.
Retzker, R. Ozeri. Phys.
Rev. Lett. 119, 220505 (2017)
3. Limits on Spectral Resolution Measurements by Quantum Probes.
A. Rotem, T. Gefen, S. Oviedo-Casado, J. Prior, S. Schmitt, Y. Burak, L.
McGuiness, F. Jelezko,
and A. Retzker. Phys. Rev. Lett. 122, 060503 (2019)
4. Correlated noise in Brownian motion allows for super resolution.
S. Oviedo-Casado, A. Rotem, R. Nigmatullin, J. Prior, A. Retzker. Sci
Rep 10, 19691 (2020)