Our Group

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Introduction

We study the foundations of quantum technologies. In particular, we study and propose theoretical methods that target quantum sensing and quantum computing. We work closely with experimental groups in the fields of NV centers in diamond, trapped ions and superconducting qubits.

Highlights

Recent Publications

Fedor Jelezko Alex Retzker Nir Bar-Gill and Genko T. Genov, Yachel Ben-Shalom. 8/7/2020. “Efficient and robust signal sensing by sequences of adiabatic chirped pulses.” Phys. Rev. Research , 2, 3. Publisher's Version Abstract
We propose a scheme for sensing of an oscillating field in systems with large inhomogeneous broadening and driving field variation by applying sequences of phased, adiabatic, chirped pulses. These act as a double filter for dynamical decoupling, where the adiabatic changes of the mixing angle during the pulses rectify the signal and partially remove frequency noise. The sudden changes between the pulses act as instantaneous π pulses in the adiabatic basis for additional noise suppression. We also use the pulses' phases to correct for other errors, e.g., due to nonadiabatic couplings. Our technique improves significantly the coherence time in comparison to standard XY8 dynamical decoupling in realistic simulations in NV centers with large inhomogeneous broadening. Beyond the theoretical proposal, we also present proof-of-principle experimental results for quantum sensing of an oscillating field in NV centers in diamond, demonstrating superior performance compared to the standard technique.
D. Cohen, A.Retzker, M.Eldar, and R.Nigmatullin. 6/15/2020. “Confined Nano‐NMR Spectroscopy Using NV Centers.” Advanced Quantum Technologies. Publisher's Version Abstract
Nano nuclear magnetic resonance (nano‐NMR) spectroscopy with nitrogen‐vacancy (NV) centers holds the potential to provide high‐resolution spectra of minute samples. This is likely to have important implications for chemistry, medicine, and pharmaceutical engineering. One of the main hurdles facing the technology is that diffusion of unpolarized liquid samples broadens the spectral lines thus limiting resolution. Experiments in the field are therefore impeded by the efforts involved in achieving high polarization of the sample which is a challenging endeavor. Here, a scenario where the liquid is confined to a small volume is examined. It is shown that the confinement “counteracts” the effect of diffusion, thus overcoming a major obstacle to the resolving abilities of the NV‐NMR spectrometer.
D. Cohen, T.Gefen, L.Ortiz, and A.Retzker. 9/18/2020. “Achieving the ultimate precision limit with a weakly interacting quantum probe.” npj Quantum Information , 6, 83. Publisher's Version Abstract
The ultimate precision limit in estimating the Larmor frequency of N unentangled qubits is well established, and is highly important for magnetometers, gyroscopes, and other types of quantum sensors. However, this limit assumes perfect projective measurements of the quantum registers. This requirement is not practical in many physical systems, such as NMR spectroscopy, where a weakly interacting external probe is used as a measurement device. Here, we show that in the framework of quantum nano-NMR spectroscopy, in which these limitations are inherent, the ultimate precision limit is still achievable using control and a finely tuned measurement.
Yotam V, Benedikt T, Tuvia G, Ilai S, Martin P, and Alex R. 9/8/2020. “Robustness of the NV-NMR Spectrometer Setup to Magnetic Field Inhomogeneities.” Physical Review Letters, 125, 110502. Publisher's Version Abstract
The NV-NMR spectrometer is a promising candidate for detection of NMR signals at the nanoscale. Field inhomogeneities, however, are a major source of noise that limits spectral resolution in state of the art NV-NMR experiments and constitutes a major bottleneck in the development of nanoscale NMR. Here we propose, a route in which this limitation could be circumvented in NV-NMR spectrometer experiments, by utilizing the nanometric scale and the quantumness of the detector.
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