Simple, robust, and on-demand generation of single and correlated photons

Abstract

We propose two different setups to generate single photons on demand using an atom in front of a mirror, along with either a beam splitter or a tunable coupling. We show that photon-generation efficiency of ∼99% is straightforward to achieve. The proposed schemes are simple and easily tunable in frequency. The operation is relatively insensitive to dephasing and can be easily extended to generate correlated pairs of photons. They can also, in principle, be used to generate any photonic qubit of the form μ|0 + ν|1 in arbitrary wave packets, making them very attractive for quantum communication applications.

Correlations and Entanglement of Microwave Photons Emitted in a Cascade Decay

“…Here we have met these requirements by using a superconducting artificial atom, coherently driven to its second-excited state and decaying into a well-defined microwave mode.Our results highlight the coherent nature of cascade decay and demonstrate a novel protocol to generate entanglement between itinerant field modes.We have realized a photon source (Fig. 1) based on a transmon-type qubit [11,12], with two lowest transitions at ω ge /2π = 7.0975 GHz and ω ef /2π = 6.8645 GHz between the ground, |g , the first excited, |e , and the second excited state, |f , and a resulting anharmonicity α/2π = −233 MHz. The transmon is driven via a weakly coupled input port [13,14] and decays into one of the two input ports of the single-pole, double-throw switch described in Ref.…”

“…Our results highlight the coherent nature of cascade decay and demonstrate a novel protocol to generate entanglement between itinerant field modes.We have realized a photon source (Fig. 1) based on a transmon-type qubit [11,12], with two lowest transitions at ω ge /2π = 7.0975 GHz and ω ef /2π = 6.8645 GHz between the ground, |g , the first excited, |e , and the second excited state, |f , and a resulting anharmonicity α/2π = −233 MHz. The transmon is driven via a weakly coupled input port [13,14] and decays into one of the two input ports of the single-pole, double-throw switch described in Ref.…”

Full two-photon down-conversion of a single photon

“…When classical light is used as input, only a small part of the incident power is converted into a correlated twophoton output field [21][22][23]. In chiral waveguides, however, it has been argued that two photons can be generated when one and only one photon is scattered in a C3LS structure [24].…”

Causality in quantum field theory with classical sources

“…This simple example demonstrates the fundamental difference between the role of the superposition principle in classical and in quantum physics. It is a remarkable achievement of experimental quantum optics that such quantum-mechanical interference effects between the vacuum state and a single-photon state have been observed [31,32] (for a related discussions also see [33][34][35][36][37]). In the next section we extend this simple single-mode case to the general multi-mode space-time dependent situation.…”