Coherent control of the silicon-vacancy spin in diamond

Abstract

Spin impurities in diamond have emerged as a promising building block in a wide range of solid-state-based quantum technologies. The negatively charged silicon-vacancy centre combines the advantages of its high-quality photonic properties with a ground-state electronic spin, which can be read out optically. However, for this spin to be operational as a quantum bit, full quantum control is essential. Here we report the measurement of optically detected magnetic resonance and the demonstration of coherent control of a single silicon-vacancy centre spin with a microwave field. Using Ramsey interferometry, we directly measure a spin coherence time, T2*, of 115±9 ns at 3.6 K. The temperature dependence of coherence times indicates that dephasing and decay of the spin arise from single-phonon-mediated excitation between orbital branches of the ground state. Our results enable the silicon-vacancy centre spin to become a controllable resource to establish spin-photon quantum interfaces.

Silicon-Vacancy Spin Qubit in Diamond: A Quantum Memory Exceeding 10 ms with Single-Shot State Readout

“…These optical properties were recently used to show strong interactions between single photons and single SiV − centers and to probabilistically entangle two SiV − centers in a single nanophotonic device [16]. At 4 K, however, the SiV − spin coherence is limited to ∼ 100 ns due to coupling to the phonon bath, mediated by the spin-orbit interaction [17][18][19][20][21].In this Letter, we demonstrate high-fidelity coherent manipulation and single-shot readout of individual SiV − spin qubits in a dilution refrigerator. In particular, we extend the coherence time of the SiV − electronic spin by five orders of magnitude to 13 ms by operating at 100 mK [22].…”

“…Application of a magnetic field lifts the spin degeneracy and allows the use of the spin sublevels |↓ and |↑ of the LB as qubit states. At 4 K, the SiV − spin coherence is limited to ∼ 100 ns [17][18][19][20][21] due to interactions with the thermal acoustic phonon bath at frequency ∆ GS ∼ 50 GHz. These interactions result in a relaxation at rates γ + and γ − between the levels in the LB and the UB with different orbitals and the same spin projections as shown in Fig.…”

Tin-Vacancy Quantum Emitters in Diamond

“…This limitation originates from phonon-mediated transitions between the lower and upper branches in the ground state [13][14][15][16]. Further cooling down to the sub-Kelvin regime or strain engineering is considered as a solution [15,16]. Another possibility is creation of a novel color center possessing a larger energy splitting in the ground state.…”

“…To overcome these drawbacks, color centers based on IV group elements, silicon-vacancy (SiV) [5][6][7] and germanium-vacancy (GeV) [8][9][10][11] centers, has attracted attention owing to their large ZPL, structural symmetry robust against the external noise, and availability of quantum emission by single centers. Recently, spin control and evaluation of spin coherence time have been investigated for this two color centers [12][13][14][15][16], revealing that their spin coherence times were limited to sub-microseconds even at cryogenic temperatures < 5 K, much shorter than that of the NV center [17,18]. This limitation originates from phonon-mediated transitions between the lower and upper branches in the ground state [13][14][15][16].…”

“…Recently, spin control and evaluation of spin coherence time have been investigated for this two color centers [12][13][14][15][16], revealing that their spin coherence times were limited to sub-microseconds even at cryogenic temperatures < 5 K, much shorter than that of the NV center [17,18]. This limitation originates from phonon-mediated transitions between the lower and upper branches in the ground state [13][14][15][16]. Further cooling down to the sub-Kelvin regime or strain engineering is considered as a solution [15,16].…”