No Arabic abstract
A rotation sensor is one of the key elements of inertial navigation systems and compliments most cellphone sensor sets used for various applications. Currently, inexpensive and efficient solutions are mechanoelectronic devices, which nevertheless lack long-term stability. Realization of rotation sensors based on spins of fundamental particles may become a drift-free alternative to such devices. Here, we carry out a proof-of-concept experiment, demonstrating rotation measurements on a rotating setup utilizing nuclear spins of an ensemble of NV centers as a sensing element with no stationary reference. The measurement is verified by a commercially available MEMS gyroscope.
We propose a protocol that achieves arbitrary N-qubit interactions between nuclear spins and that can measure directly nuclear many-body correlators by appropriately making the nuclear spins interact with a nitrogen vacancy (NV) center electron spin. The method takes advantage of recently introduced dynamical decoupling techniques and demonstrates that action on the electron spin is sufficient to fully exploit nuclear spins as robust quantum registers. Our protocol is general, being applicable to other nuclear spin based platforms with electronic spin defects acting as mediators as the case of silicon carbide.
We demonstrate operation of a rotation sensor based on the $^{14}$N nuclear spins intrinsic to nitrogen-vacancy (NV) color centers in diamond. The sensor employs optical polarization and readout of the nuclei and a radio-frequency double-quantum pulse protocol that monitors $^{14}$N nuclear spin precession. This measurement protocol suppresses the sensitivity to temperature variations in the $^{14}$N quadrupole splitting, and it does not require microwave pulses resonant with the NV electron spin transitions. The device was tested on a rotation platform and demonstrated a sensitivity of 4.7 $^{circ}/sqrt{rm{s}}$ (13 mHz/$sqrt{rm{Hz}}$), with bias stability of 0.4 $^{circ}$/s (1.1 mHz).
Initializing a set of qubits to a given quantum state is a basic prerequisite for the physical implementation of quantum-information protocols. Here, we discuss the polarization of the electronic and nuclear spin in a single nitrogen vacancy center in diamond. Our initialization scheme uses a sequence of laser, microwave and radio-frequency pulses, and we optimize the pumping parameters of the laser pulse. A rate equation model is formulated that explains the effect of the laser pulse on the spin system. We have experimentally determined the population of the relevant spin states as a function of the duration of the laser pulse by measuring Rabi oscillations and Ramsey-type free-induction decays. The experimental data have been analyzed to determine the pumping rates of the rate equation model.
We experimentally investigate the protection of electron spin coherence of nitrogen vacancy (NV) center in diamond by dynamical nuclear polarization. The electron spin decoherence of an NV center is caused by the magnetic ield fluctuation of the $^{13}$C nuclear spin bath, which contributes large thermal fluctuation to the center electron spin when it is in equilibrium state at room temperature. To address this issue, we continuously transfer the angular momentum from electron spin to nuclear spins, and pump the nuclear spin bath to a polarized state under Hartman-Hahn condition. The bath polarization effect is verified by the observation of prolongation of the electron spin coherence time ($T_2^*$). Optimal conditions for the dynamical nuclear polarization (DNP) process, including the pumping pulse duration and depolarization effect of laser pulses, are studied. Our experimental results provide strong support for quantum information processing and quantum simulation using polarized nuclear spin bath in solid state systems.
Hybrid quantum registers consisting of different types of qubits offer a range of advantages as well as challenges. The main challenge is that some types of qubits react only slowly to external control fields, thus considerably slowing down the information processing operations. One promising approach that has been tested in a number of cases is to use indirect control, where external fields are applied only to qubits that interact strongly with resonant excitation pulses. Here we use this approach to indirectly control the nuclear spins of an NV center, using microwave pulses to drive the electron spin, combined with free precession periods optimized for generating logical gate operations on the nuclear spins. The scheme provides universal control and we present two typical applications: polarizing the nuclear spin and measuring nuclear spin free induction decay signals, both without applying radio-frequency pulses. This scheme is versatile as it can be implemented over a wide range of magnetic field strengths and at any temperature.