Spin-Mechanical Scheme with Color Centers in Hexagonal Boron Nitride Membranes

Abstract

Recently observed quantum emitters in hexagonal boron nitride (hBN) membranes have a potential for achieving high accessibility and controllability thanks to the lower spatial dimension. Moreover, these objects naturally have a high sensitivity to vibrations of the hosting membrane due to its low mass density and high elasticity modulus. Here, we propose and analyze a spin-mechanical system based on color centers in a suspended hBN mechanical resonator. Through group theoretical analyses and ab initio calculation of the electronic and spin properties of such a system, we identify a spin doublet ground state and demonstrate that a spin-motion interaction can be engineered which enables ground state cooling of the mechanical resonator. We also present a toolbox for initialization, rotation, and readout of the defect spin qubit. As a result the proposed setup presents the possibility for studying a wide range of physics. To illustrate its assets, we show that a fast and noise resilient preparation of a multicomponent cat state and a squeezed state of the mechanical resonator is possible; the latter is achieved by realizing the extremely detuned, ultrastrong coupling regime of the Rabi model, where a phonon superradiant phase transition is expected to occur.

Initialization and read-out of intrinsic spin defects in a van der Waals crystal at room temperature

“…This stimulates further research in hBN-based heterostructures for quantum sensing applications and drives interest into deterministically engineering single centres. The work will also accelerate the research into the spin-optomechanics with hBN, particularly given the established theoretical framework 31 and advances in nanofabrication of resonators 32 . Further, with an increased control over isotopic purity, coherent manipulation of spin states may become feasible, yielding potentially high coherence times-as predicted theoretically 33 .…”

Optical Absorption and Emission Mechanisms of Single Defects in Hexagonal Boron Nitride

“…Some color centers, such as the nitrogen vacancy (NV) center in diamond [6][7][8][9][10][11], are bright enough to be investigated in the single defect limit using single-molecule microscopy techniques [12,13]. While diamond is the most celebrated host material, the last several years have witnessed the discovery of defect-based single photon sources in SiC [1,[14][15][16][17][18][19][20], ZnO [21][22][23][24][25][26], GaN [27], WSe2 [28][29][30], WS2 [31], and hexagonal boron nitride (h-BN) [32][33][34][35][36][37][38][39][40][41][42][43][44][45]. The latter three materials exist as two-dimensional monolayers and layered solids, thus offering the possibility of integrating single-photon sources with van der Waals heterostructure devices for tuning and other control.…”

“…Defect emission in h-BN can be ultrabright [32], have a narrow linewidth [33], be tuned [39], and remain photostable up to 800 K [41]. These positive attributes have sparked strong interest in h-BN defects from research groups around the world [32][33][34][35][36][37][38][39][40][41][42][43][44][45]. Despite this surge of interest, most works have focused on characterizing the phenomenology of h-BN emission, leaving open several difficult to answer questions regarding the fundamental nature of h-BN quantum emitters.…”

Hexagonal Boron Nitride Phononic Crystal Waveguides

“…Agreeing with the band structure simulation, clear stop bands (<15 MHz) can be observed with displacement ratio lower than ˗90 dB for all the presented cases. Conversely, there is no noticeable relative amplitude decline at the predicted bandgap frequencies (24)(25)(26)(27) for the lattice with N=10. For N=20 and 40 cases, attenuation of ~30 dB and ~90 dB can be achieved, respectively.…”

“…In the quantum regime, mechanical resonators can be coupled to artificial atoms embodied as charge qubits or spin qubits through Coulomb interactions or magnetic dipole forces, respectively [12,16, 25 , 26 ]. Specifically and intriguingly, spin-mechanical coupling schemes have been recently proposed and theoretically investigated based on the h-BN quantum emitters [27,28].…”