Abstract We propose an electromechanical scheme where the electronic degrees of freedom of boron vacancy color centers hosted by a hexagonal boron nitride (hBN) nanoribbon are coupled for quantum information processing. The mutual coupling of color centers is provided via their coupling to the mechanical motion of the ribbon, which in turn stems from the local strain. The coupling strengths are computed by performing ab initio calculations. The density functional theory results for boron vacancy centers on boron nitride monolayers reveal a huge strain susceptibility. In our analysis, we take into account the effect of all flexural modes and show that despite the thermal noise introduced through the vibrations one can achieve steady-state entanglement between two and more number of qubits that survives even at room temperature. Moreover, the entanglement is robust against mis-positioning of the color centers. The effective coupling of color centers is engineered by positioning them in the proper positions. Hence, one is able to tailor stationary graph states. Furthermore, we study the quantum simulation of the Dicke–Ising model and show that the phonon non-equilibrium phase transition occurs even for a finite number of color centers. Given the steady-state nature of the proposed scheme and accessibility of the electronic states through optical fields, our work paves the way for the realization of steady-state quantum information processing with color centers in hBN membranes.
Abstract We propose an electromechanical scheme where the electronic degrees of freedom of boron vacancy color centers hosted by a hexagonal boron nitride (hBN) nanoribbon are coupled for quantum information processing. The mutual coupling of color centers is provided via their coupling to the mechanical motion of the ribbon, which in turn stems from the local strain. The coupling strengths are computed by performing ab initio calculations. The density functional theory results for boron vacancy centers on boron nitride monolayers reveal a huge strain susceptibility. In our analysis, we take into account the effect of all flexural modes and show that despite the thermal noise introduced through the vibrations one can achieve steady-state entanglement between two and more number of qubits that survives even at room temperature. Moreover, the entanglement is robust against mis-positioning of the color centers. The effective coupling of color centers is engineered by positioning them in the proper positions. Hence, one is able to tailor stationary graph states. Furthermore, we study the quantum simulation of the Dicke–Ising model and show that the phonon non-equilibrium phase transition occurs even for a finite number of color centers. Given the steady-state nature of the proposed scheme and accessibility of the electronic states through optical fields, our work paves the way for the realization of steady-state quantum information processing with color centers in hBN membranes.
Recent observation of quantum emitters in monolayers of hexagonal boron nitride (h-BN) has provided a novel platform for optomechanical experiments where the single-photon emitters can couple to the motion of a freely suspended h-BN membrane. Here, we propose a scheme where the electronic degree of freedom (d.o.f.) of an embedded color center is coupled to the motion of the hosting h-BN resonator via dispersive forces. We show that the coupling of membrane vibrations to the electronic d.o.f. of the emitter can reach the strong regime. By suitable driving of a three-level Λ-system composed of two spin d.o.f. in the electronic ground state as well as an isolated excited state of the emitter, a multiple electromagnetically induced transparency spectrum becomes available. The experimental feasibility of the efficient vibrational ground-state cooling of the membrane via quantum interference effects in the two-color drive scheme is numerically confirmed. More interestingly, the emission spectrum of the defect exhibits a frequency comb with frequency spacings as small as the fundamental vibrational mode, which finds applications in high-precision spectroscopy.
In this paper, we focus on a scheme in which three high-quality-factor mechanical modes of a hexagonal boron nitride (hBN) membrane monolayer are coupled to a common optically addressable spin defect present in the membrane via magnetic field interaction. We show that this coupling induces an effective phonon-phonon interaction in the dispersive regime and under appropriate magnetic field and microwave modulation. We derive the Langevin-Heisenberg equations of motion for vibrational modes to analyze optimal parameter regimes for reaching a physically stable system. We also investigate the effect of coupling strength on purity and entanglement. Our results demonstrate that bipartite and genuinely tripartite steady-state entanglement between different vibrational modes of hBN may be achieved in a broad spectrum of experimental parameters. This study has the potential to enable scalability to be implemented for the generation of two-dimensional continuous-variable cluster states for universal quantum computation.
Generating stable entanglement by mimicking a squeezed environment plays an important role in quantum metrology and quantum information. Here, we propose an efficient scheme for generating stable entanglement of two boron-vacancy (VB) defects in a suspended circular hexagonal boron nitride (h-BN) membrane via a two-phonon drive. Compared to other reported methods, our scheme only needs a linear resource and thus is more convenient for experimental implementation. In the presence of a gradient magnetic field, the electronic spin degree of freedom of the VB defect can be coupled to the mechanical mode of h-BN membrane through spin-phonon interaction. The coupling strength is closely related to the geometry of the magnetic field and the parameters of the membrane, which allows us to realize different coupling regimes by choosing the parameter appropriately. After applying a time-dependent pump to the h-BN membrane, we can modulate its spring constant and obtain a tunable two-phonon drive to the mechanical mode. We then investigate the dissipative coupling between two VB spins in the condition of a large dissipation limit, showing that the stable entanglement can be generated under a two-phonon drive. In addition, we also take the spin dephasing into consideration to explore the robustness of our scheme. We then extend this scheme to multiparticle systems, which shows that the entanglement degree deepens with the increase of VB spin number. This work offers a fascinating platform for generating stable entanglement with VB spins in two-dimensional h-BN.
Hyperbolic phonon polaritons (HPPs) in hexagonal boron nitride (hBN) confine mid-infrared light to deep-subwavelength scales and may offer a powerful route to strong light-matter interactions. Generation and control of HPPs are typically accessed using classical near-field probes, which limits experiments at the quantum level.A complementary frontier in hBN research focuses on color centers: bright, stable, atomically localized emitters that have rapidly emerged as a promising platform for solid-state quantum optics. Here we establish a key connection between these two directions by developing a cavity-QED framework in which a single hBN color center serves as a quantum source of HPPs. We quantify the emitter-HPP interaction and analyze two generation schemes. The first is spontaneous emission into the phonon sideband, which can produce single-HPP events and, in ultrathin slabs, becomes single-mode with an enhanced decay rate. The second is a stimulated Raman process that provides frequency selectivity, tunable conversion rate, and narrowband excitation. This drive launches spatially confined, ray-like HPPs that propagate over micrometer distances. We also outline a two-emitter correlation measurement that can directly test the single-polariton character of these emissions. By connecting color-center quantum optics with hyperbolic polaritonics, our approach enables quantum emitters to act as on-chip quantum sources and controls for HPPs, while HPPs provide long-range channels that couple spatially separated emitters. Together, these capabilities point to a new direction for mid-infrared photonic experiments that unite strong coupling, spectral selectivity, and spatial reach within a single material system.
Abstract The negatively charged boron vacancy center ( V B − ) in a hexagonal boron nitride ( h -BN) film, represents a promising quantum unit at room temperature due to its exceptional attributes, including remarkable sensitivity to magnetic field or strain, long coherence time, nearly perfect spin homogeneity, and an ultra-thin film structure. We here study a different hybridization proposal of an ensemble of V B − centres magnetically coupled to a superconducting flux qubit (FQ) or a DC superconducting quantum interference device (SQUID). Because the localization degree and density of the magnetic field in the FQ are much greater than that of the superconducting resonator (SR), this type of spins-FQ coupling is much stronger for an identical number of V B − centres, and it can therefore mimic the traditional light–matter interactions, i.e., the Dicke-, Tavis-Cummings- or Rabi-like model. For applications, this hybrid quantum system can potentially guarantee such as the simulation of quantum phase transitions (QPTs) of the anomalous Rabi-like model especially showing the influences to QPTs of the spins’ dephasing and FQ’s decay, criticality-enhanced quantum metrology or quantum sensing, the steady-state preparation of single- and two-mode spin-squeezed state (SSS). This investigation can potentially provide a platform for the subsequent quantum information processing (QIP).
Quantum emitters in hexagonal boron nitride (hBN) are promising building blocks for solid-state quantum photonics because of their bright room-temperature emission. These emitters strongly interact with lattice vibrations, which partially underpins their excitation efficiency. Here, using complementary cathodoluminescence (CL) and photoluminescence (PL) spectroscopy, we demonstrate cavity-mediated interactions between hBN quantum emitters coupled to the same plasmonic Au void cavity at the room temperature. Cathodoluminescence measurements reveal that a vibronic transition of the 443 nm emitter hybridizes with the cavity mode, giving rise to a spectrally resolved splitting, while the neighboring 537 nm emitter remains in the weak-coupling regime despite spectral overlap. The energy split of the CL peak is at the order of 36.2 meV, whereas the PL-resolved peak is approximately 24.1 meV, which is due to the collective excitations of multiple emitters per electron excitation and their mutual interactions. Maxwell-Bloch simulations reproduce the experimental spectra and identify the observed splitting as the result of cavity-induced hybridization. Excitation-dependent PL further shows that the hybridized state can be accessed through phonon-assisted excitations below the zero-phonon transition. These results demonstrate that vibronic transitions provide an effective pathway for controlling interactions between multiple quantum emitters in hybrid plasmonic nanophotonic systems.