Optical superradiance of a pair of color centers in an integrated silicon-carbide-on-insulator microresonator

Abstract

An outstanding challenge for color center-based quantum information processing technologies is the integration of optically-coherent emitters into scalable thin-film photonics. Here, we report on the integration of near-transform-limited silicon vacancy (VSi) defects into microdisk resonators fabricated in a CMOS-compatible 4H-Silicon Carbide-on-Insulator platform. We demonstrate a single-emitter cooperativity of up to 0.8 as well as optical superradiance from a pair of color centers coupled to the same cavity mode. We investigate the effect of multimode interference on the photon scattering dynamics from this multi-emitter cavity quantum electrodynamics system. These results are crucial for the development of quantum networks in silicon carbide and bridge the classicalquantum photonics gap by uniting optically-coherent spin defects with wafer-scalable, state-of-theart photonics.Color centers 1-3 are among the leading contenders for the realization of distributed quantum information processing, including communication 4,5 and computation 6 , combining a long-lived multi-qubit spin register 7 with a photonic interface in the solid state. To continue scaling up quantum networks while maintaining high entanglement generation rates, the intrinsically weak interaction between photons and color centers must be enhanced via integration into photonic resonators 5,8-13 . Efforts in cavity integration have already enabled milestone demonstrations such as cavity-mediated coherent interaction between two emitters 9 , single-emitter cooperativity exceeding 100 and spin-memory-assisted quantum communication 5 . The ultimate goal of quantum computation and error-protected communication 14 requires the realization of photonic circuits with high complexity and minimal inter-node loss, and will require bringing together all integrated photonics expertise developed in the past two decades. 15 Yet color center technologies cannot at present take advantage of the state of the art in integrated photonics, due to two central challenges. First, thin-film-oninsulator photonics technologies have been incompatible with high-quality color centers: this motivated the focus on bulk-crystal-carving methods 8,16-19 , suitable for fabrication of individual devices but restrictive in terms of large-scale monolithic photonic circuits. Second, inversion symmetry, which protects optical transitions from electric fields (to first order 20,21 ), had been widely considered to be a prerequisite for color centers to maintain optical coherence in nanophotonic structures. This notion motivates the dominant focus on group-IV color centers in diamond (SiV, SnV, GeV) 22 , and eliminates from consideration an entire class of materials that lack crystal inversion symmetry. Among these materials is silicon carbide (SiC) 23 , which has otherwise emerged as the top contender for wafer-scale integration of color centers with excellent spin-optical properties (such as the sili-con vacancy (V Si ) 19,24-27 and the divacancy 28,29 ). This

Superspontaneous Four-Wave Mixing in an Array of Silicon Microresonators

“…The quantities B (N ) j and I (N ) jk have been computed through numerical simulations using Eq. (14,15), and are shown in the Supplemental Fig. 3 [29] for both CW and pulsed excitation.…”

“…Mimicking the experimental conditions, we considered a CW pump, which allows us to write Eq. (14) in the form…”

“…Yet, with progress in materials science and nanotechnology, it is now possible to initialize a collection of single emitters in the so-called Dicke bright and dark states -i.e., the maximally super-and subradiant states -with high fidelity [5]. Moreover, selective coupling to nanophotonic waveguides or cavities can be engineered to tailor the spontaneous emission into a restricted set of radiation modes [13,14]. Recent studies have demonstrated cooperative effects between quantum emitters involving a wide variety of platforms, including superconducting qubits [15,16], quantum dots [17][18][19], trapped ions [13], cold atoms [20], and colour centers in diamond [21,22].…”

Diamond Integrated Quantum Nanophotonics: Spins, Photons and Phonons

“…Advances in spinphoton entanglement [45] paved the way for photon-mediated entanglement of remote qubits [46]- [48], culminating in the recent demonstration of a three-node quantum network [49], [50]. While these demonstrations have been fruitful, it is worth noting that parallel advances have been made with other experimental platforms including trapped atoms and ions [17], [51]- [56], superconducting resonators [57], [58], selfassembled quantum dots [59]- [61], and defect-based qubits in other wide-bandgap semiconductors and dielectrics [62]- [72].…”

Diamond Integrated Quantum Photonics: A Review

“…Advances in spinphoton entanglement [44] paved the way for photon-mediated entanglement of remote qubits [45]- [47], culminating in the recent demonstration of a three-node quantum network [48], [49]. While these demonstrations have been fruitful, it is worth noting that parallel advances have been made with other experimental platforms including trapped atoms and ions [17], [50]- [54], superconducting resonators [55], [56], self-assembled quantum dots [57]- [59], and defect-based qubits in other wide-bandgap semiconductors and dielectrics [60]- [70].…”