Tuneable on-demand single-photon source in the microwave range

Abstract

An on-demand single-photon source is a key element in a series of prospective quantum technologies and applications. Here we demonstrate the operation of a tuneable on-demand microwave photon source based on a fully controllable superconducting artificial atom strongly coupled to an open-ended transmission line. The atom emits a photon upon excitation by a short microwave π-pulse applied through a control line. The intrinsically limited device efficiency is estimated to be in the range 65–80% in a wide frequency range from 7.75 to 10.5 GHz continuously tuned by an external magnetic field. The actual demonstrated efficiency is also affected by the excited state preparation, which is about 90% in our experiments. The single-photon generation from the single-photon source is additionally confirmed by anti-bunching in the second-order correlation function. The source may have important applications in quantum communication, quantum information processing and sensing.

On-Demand Microwave Generator of Shaped Single Photons

“…In recent years, experiments have demonstrated basic operations of a single qubit interacting with propagating modes such as resonance fluorescence [16], a single-photon router [17], quantum-state filtering [18], and photon-mediated interactions [19,20]. Recent experiments using transmission lines have demonstrated a frequency-tunable single-photon source with a flux qubit capacitively coupled to two semi-infinite lines [21] and the correlated emission of photons at two different frequencies using a transmon qubit [22]. Both experiments used fixed qubit-line couplings.…”

Finite sizes and smooth cutoffs in superconducting circuits

“…This is particularly interesting since short-time qubit-line interactions are desired for the generation of so-called single-photon states (i.e. states with low expectation values of the number operator) [18,19]. Additionally, theoretical predictions of states generated through short interaction times have very wide distributions in frequency space, so it is important to take into account how the interaction strength behaves at high frequencies.…”

Multiplexing Superconducting Qubit Circuit for Single Microwave Photon Generation

“…An alternative approach to the single microwave photon generation is based on an artificial superconducting atom directly coupled to an open-end transmission line, a 1D analogue of the 3D half-space [12]. Here we report on a design comprising eight resonators, each housing a superconducting transmon qubit [13] that exhibits good coherence properties.…”