Telecom photon interface of solid-state quantum nodes

Abstract

Solid-state spins such as nitrogen-vacancy (NV) center are promising platforms for large-scale quantum networks. Despite the optical interface of NV center system, however, the significant attenuation of its zero-phonon-line photon in optical fiber prevents the network extended to long distances. Therefore a telecom-wavelength photon interface would be essential to reduce the photon loss in transporting quantum information. Here we propose an efficient scheme for coupling telecom photon to NV center ensembles mediated by rare-earth doped crystal. Specifically, we proposed protocols for high fidelity quantum state transfer and entanglement generation with parameters within reach of current technologies. Such an interface would bring new insights into future implementations of long-range quantum network with NV centers in diamond acting as quantum nodes. IntroductionQuantum network based on solid-state quantum memories are a promising platform for long range quantum communication and remote sensing [1][2][3]. Quantum nodes in a network require robust storage, high fidelity and efficient interface to achieve these demanding applications. Among many physical platforms, nitrogen vacancy (NV) centers stand out for their very long coherence time in the ground states, making them ideal systems to be used as stationary nodes for quantum computer or sensor networks. Microwave and optical interfaces have provided the NV system with a flexible toolset of control knobs, as required in many emerging technologies. This has enabled a recent demonstration of deterministic entanglement generation between two NV centers in diamond [4] with an entanglement rate of about 40 Hz. Despite these successes, NV centers present some shortcomings for quantum communication applications: the NV spin has a zero phonon line (ZPL) at 637 nm and it only corresponds to 3% of the total emission.The propagation loss in optical fibers at this wavelength (8 dB/km) is much larger compared with telecommunication ranges (less than 0.2 dB/km). To extend the entanglement generation scheme to large distance would thus benefit from using a telecom photon interface. The conventional way to overcome this limit is to perform parametric down conversion to convert the photons into telecom-wavelength photons (tele-photons), as demonstrated in several systems including quantum dots [5][6][7], trapped ions [8-10] and atomic ensembles [11][12][13].The low emission rate into the ZPL limits the rate of entanglement generation. The emission fraction into the ZPL could be enhanced by a microcavity via the Purcell effect [14], while a difference frequency generation, used in recent experiments, achieved conversion of single NV photons into telecom wavelength with 17% efficiency [15,16]. However, the signal-to-noise ratio was limited by pump-induced noise in the conversion process [17,18] and resonance driving at cryogenic temperature is required, preventing room temperature applications.An alternative approach is to work with the microwave interface of NV centers and then ...

Effective routing design for remote entanglement generation on quantum networks

“…Recent experiments 7 have demonstrated deterministic entanglement between two spatially separated solid-state memories via optical photons. The distance in this physical (hardware) layer 8 can be further increased with low-loss optical links, such as transporting photons at the tele-communication wavelength [9][10][11] .…”

Quantum State Transfer with Seamless Frequency‐Connection Through Diamond Optomechanical Cavity

“…We assume that the cavity is driven in the red resolved sideband (which satisfies ) and there is no population on the excited state , the effective interaction Hamiltonian linear to the mechanical displacement can be derived as where , . Different from the previous work where both of the dipole transitions are driven resonantly by optical fields, [ 18–22 ] we use the sideband transitions, where the mechanical mode and optical field drive the optical transition together, enabling the selective coupling of the electron spin to any relevant mechanical mode. Specifically, to achieve seamless frequency‐connection between spin and mechanical modes, we set the detuning between the two optical fields as .…”

“…[ 17 ] Another is to work with the microwave interface of solid state spins and then up‐convert the signal to the telecom‐wavelength domain, which can be realized with the electro‐optic effects [ 18,19 ] or rare‐earth doped crystals. [ 20 ] In the above two ways, the driving frequency must be strictly resonant with the transition frequency of the solid‐state emitter.…”

Controllable quantum interface between itinerant optical photon and microwave photonic memory

“…By taking advantage of the low loss of silica in particular frequency range [8] the optical communication can be realized in the realistic quantum internet, yielding a possibility of transferring quantum information over long distance [9]. A lot of studies have been devoted to implementing the interface between itinerant optical photonic qubits and the memory qubits, such as NV centers [10][11][12], superconducting qubits [13][14][15][16] and cold atoms [17,18].…”

“…Among them, the rare earth doped crystal is of great interest, particularly the Er 3+ ions [29]. In references [12,14,25], schemes were proposed for coherently transferring quantum information in optical range to microwave range with rare earth doped crystal. Most of the schemes follow the two-step protocol: the states of optical cavity were first converted to the collective spin excitations, then transferred and stored in the NV center ensemble [12] or the artificial atoms [14,25].…”