Quantum measurement of a rapidly rotating spin qubit in diamond

Abstract

Single-qubit sensing in a physically rotating reference frame with defect centers in diamond.

T2 -limited sensing of static magnetic fields via fast rotation of quantum spins

“…The experimental setup and methods are depicted in Fig. 1 and are similar to those described previously [18,19]. A diamond containing an ensemble of NV centers is mounted to the spindle of an electric motor that rotates at 200,000 rpm (3.33 kHz).…”

“…The strong field gradients from the tip resulted in modulation of the NV Zeeman shift with the tip movement, and spin-echo magnetometry measured the up-converted DC magnetic field. Up-conversion with sensor rotation as demonstrated in our work relies on the vector properties of the magnetic field, rather than modulating the source of the magnetic field to be measured, and is therefore equally applicable to microscale sensing with rotating single qubits [19] and macroscopic sensing with large ensembles of NV sensors.…”

“…In this work, we demonstrate a quantum magnetometry method based on an ensemble of rotating spin qubits which can detect DC magnetic fields with a sensitivity ultimately limited by T 2 , rather than T * 2 . Our technique upconverts the DC magnetic field to AC by rotating the host diamond crystal with a period comparable to T 2 [18,19] in a way that modulates the coupling between the NV center and the magnetic field to be detected. With the NV crystal axis at an angle θ NV to the rotation axis and a small target DC magnetic field transverse to the rotation axis, the Zeeman shift of the NV is modulated at the rotation frequency in proportion to the DC field.…”

Observation of a Quantum Phase from Classical Rotation of a Single Spin

“…Quantum systems are also affected by physical rotation, but in most cases meaningful observation or exploitation of the effects is challenging due to the difficulties associated with controllably rotating an addressable quantum system at rates comparable to the coherence time of the system. Solid-state spin qubits such as the nitrogen-vacancy (NV) center in diamond [1,2] provide promising testbeds of how classical rotation affects quantum systems [3], due to their long coherence times of up to several milliseconds [4] and the robust nature of the host substrate. As the natural quantization axis of the NV is set by the host diamond crystal orientation, rotating the crystal rotates the qubit, and the effects of other phenomena such as magnetic fields can be examined independently [5,6].…”

“…1 and the specific experimental configuration we use is similar to that described previously in Ref. [3]. A 99.99 % 12 C diamond is mounted on its (100) face to an electric motor that spins at ω rot = 3.33 kHz about an axis z.…”