报告一：

报告时间：2017年10月31日上午09:15-10:00

报告地点：近代物理系210会议室

报告人：林毅恒博士后，JILA institute

报告题目：Microwave polarization measurement with optically trapped atoms

简介：We reconstruct microwave polarization ellipse by driving resonant transitions between hyperfine ground states of $^{87}$Rb atoms trapped in optical tweezers.  The resonant Rabi rates of $\sigma_{\pm,\pi}$ transitions corresponds to respective microwave polarization components, projected along the direction of an externally applied bias magnetic field. By measuring the Rabi rate of each transitions at two non-overlapping bias field, we obtain sufficient information to reconstruct the strength of each microwave polarization components as well as their relative phases, producing a microwave polarization ellipse in the lab frame. To test the result we predict transition Rabi rates for various bias field directions, which is matched with experimental measurements. This technique can be applied to other systems, for example trapped ions, nitrogen-vacancy centers and Rydberg atoms, and can be used for vectorial measurements of microwave and optical fields.

报告二：

报告时间：2017年10月31日上午10:00-11:00

报告地点：近代物理系210会议室

报告人：Milos Nesladek，University Hasselt and IMOMEC division IMEC, B 3591 Hasselt, Belgium

报告题目：Electrically Detected Magnetic Resonance of NV Spin States in Diamond: Towards Coherent Driving and readout of Single Spin Qubits.

简介：Scalable principles for quantum state readout are one of open questions in quantum technology. Building on the recent results of photoelectric detection of magnetic resonances (PDMR)  [1,2] we discuss the prospect of PDMR technique for solid-state qubit devices in diamond. One of the key PDMR advantages over the optical detected magnetic resonance  (ODMR) technique are the high detection rates ~ 5 x 109 s-1, exceeding orders of magnitude ODMR. Consequently, the novel detection technique might lead to the single shot readout of the NV centres quantum state and provide fast data acquisition at room temperature.  To achieve this goal we discuss the photoelectric gain, used to obtain high detection rates on small NV spin qubit ensembles. The photophysics of the transitions on NV centre is reviewed and several scenarios for obtaining highest single/noise ratio are presented. We demonstrate pulsed PDMR measurements, compatible with coherent manipulation of the spin states realized on quantum chips. Finally we realize a single NV qubits read electrically.

We discuss another defects such as NiV as a potential candidate for electrically read spin qubits in diamond.

[1] E. Bourgeois et al Nat. Comm. 6, 8577 (2015).

[2] M. Gulka et al, Phys. Rev. Applied 7, 044032, (2017)

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