We present a detailed study of the generation of photon pairs by spontaneous four-wave mixing in a bicavity system with a single atom inside. Cavity modes lead to larger coupling strength than that of the normally assumed thermal vacuum, and thus higher generation rates are expected. Unlike approaches that have emerged so far, this paper presents an approach based on the solution of the master equation. This method allows us to investigate the photon statistics more strictly, and we show that the choices of pumping detuning and leaking rate of the cavities significantly affect the degree of the autocorrelation, and a higher-purity heralded single photon source is possible. We also derive a concise expression for the output state and the generation rate for the extreme cases where the cavity leaking rate is much smaller or larger than the rate of spontaneous emission.
We present a detailed study of the generation of photon pairs by spontaneous four-wave mixing in a bicavity system with a single atom inside. Cavity modes lead to larger coupling strength than that of the normally assumed thermal vacuum, and thus higher generation rates are expected. Unlike approaches that have emerged so far, this paper presents an approach based on the solution of the master equation. This method allows us to investigate the photon statistics more strictly, and we show that the choices of pumping detuning and leaking rate of the cavities significantly affect the degree of the autocorrelation, and a higher-purity heralded single photon source is possible. We also derive a concise expression for the output state and the generation rate for the extreme cases where the cavity leaking rate is much smaller or larger than the rate of spontaneous emission.
We theoretically investigate the coherent manipulation of biphoton generation via spontaneous four-wave mixing in a cavity-QED system with a single atom. The atom is driven by pumping, coupling, and driving fields, and the generation of the Stokes and anti-Stokes photons are enhanced by two cavities. By solving the master equation in the steady state, we analyze the spectral brightness, as well as the degree of the auto-correlation and cross-correlation. Our results show that when the pumping and driving fields are in two-photon resonance, the dark state established between the ground and Rydberg states. efficiently enhances the controllability of the driving field over the biphoton generation and the quantum statistics. In contrast, under large two-photon detuning, the control capability of the driving field is significantly reduced. The coupling field, which directly relates to the electromagnetically induced transparency, modifies the linewidth of the biphoton, while the atom-cavity coupling strength only changes the brightness without affecting the linewidth.
In this paper we study the generation of photon pairs through the process of spontaneous four wave mixing (SFWM) in a χ (3) cavity. Our key interest is the generation of photon pairs in a guided-wave configuration—fiber or waveguide—where at least one of the photons in a given pair is matched in frequency and bandwidth to a particular atomic transition, as required for the implementation of photon–atom interfaces. We present expressions, along with plots, for the two-photon joint intensity both in the spectral and temporal domains. We also present expressions for the absolute brightness, along with numerical simulations, and show that the presence of the cavity can result in a flux enhancement relative to an equivalent source without a cavity.
We present a detailed study of the generation of photon pairs by spontaneous four-wave mixing in a structure composed of two linearly uncoupled resonators, where energy can be transferred from one resonator to another only through a nonlinear interaction. Specifically, we consider the case of two racetrack-shaped resonators connected by a coupler designed to guarantee that the resonance comb of each resonator can be tuned independently and to allow the nonlinear interaction between modes that belong to different combs. We show that such a coupler can be realized in at least two ways: A directional coupler or a Mach-Zehnder interferometer. For these two scenarios, we derive analytic expressions for the pair-generation rate via single-pump spontaneous four-wave mixing and compare these results with that achievable in a single-ring resonator.
Integrated quantum photonics relies critically on photon sources that have great purity, single-mode property, scalability, integrability and flexibility for both integrated quantum computing and long-haul quantum communication. Here we report a photon-pair/single-photon source that utilizes cavity-enhanced four-wave mixing in a high-Q silicon microresonator. The photon-pair source has a spectral brightness of 6:25 × 108 pairs/s/mW2/GHz and a quantum cross-correlation of g(2)si (0) = (2:58 ± 0:16) × 104. The generated photons are single-mode, with a quantum self-correlation of 1:87 ± 0:05. The heralded single photons has conditional photon autocorrelation gc(2) as low as 0:0075 ± 0:0017 at 5:9 × 104 pair/s.
Two-photon states are essential for fundamental applications in quantum information. One of the primary methods of two-photon generation is based on parametric down-conversion, but this suffers from low efficiency and a large footprint. This work presents a detailed theoretical investigation of an alternative approach: two-photon generation from an emitter in a doubly resonant cavity. The system is modelled by the Lindblad master Equation, and an approximate analytical solution is derived to determine the experimentally achievable limits on efficiency and brightness. Additionally, the optimal cavity parameters for achieving these limits are also identified. For experimentally feasible parameters, the maximum efficiency is approximately 35%, which is significantly higher than that of parametric down-conversion-based methods. The optimal rate and efficiency for two-photon generation are achieved when the outcoupling rate of the cavity mode at the two-photon emission frequency matches the single-photon atom-field coupling strength. Moreover, the outcoupling rate of the cavity mode at the one-photon emission frequency for single photons should be minimized. The cavity field properties are also examined by studying the second-order correlation function at zero time delay and the Mandel Q parameter, revealing highly bunched two-photon emission and super-Poissonian statistics. The quantum-jump framework, combined with Monte Carlo simulations, is used to characterize the mechanism of two-photon emission and the emission spectra of the cavity. Two-photon emission is demonstrated to be a rapid cascade process of quantum jumps, and its spectrum consists of three prominent peaks corresponding to transitions between the dressed states of the system.
We present a general model, based on a Hamiltonian approach, for the joint quantum state of photon pairs generated through pulsed spontaneous four-wave mixing, including nonlinear phase modulation and a finite material response time. For the case of a silica fiber, it is found that the pair-production rate depends weakly on the waveguide temperature, due to higher-order Raman scattering events, and more strongly on pump-pair frequency detuning. From the analytical model, a numerical scheme is derived, based on the well-known split-step method. This scheme allows computation of joint states where nontrivial effects are included, such as group-velocity dispersion and Raman scattering. In this work, the numerical model is used to study the impact of the noninstantaneous response on the prefiltering purity of heralded single photons. We find that for pump pulses shorter than 1 ps, a significant detuning-dependent change in quantum-mechanical purity may be observed in silica. This shows that Raman scattering not only introduces noise, but can also drastically change the spectral correlations in photon pairs when pumped with short pulses.