Single photon sources and applications

Anjali Jatwani, Amit Verma

A single-photon source is a key advancement for quantum computing, quantum sensing, metrology, and quantum communication. These applications use single photons and have demanding standards for the effectiveness of single-photon generation. All available single photon source (SPS) is probabilistic and the search for deterministic SPS is challenging and relatively new. In this work, we explore a quantitative approach that can be applied to various sources with well-defined mathematical distribution functions in photon emission. If we have a photon number distribution, then we can easily compute the possibility of emission of a single photon from the source. Here, we observe the single photon possibility in a quantum state named as New Generalised Binomial State. Furthermore, this criterion has been applied to a single photon added New Generalised Binomial state and a single photon subtracted New Generalised Binomial State too. This technique helps us to characterize the quality of a single photon source. We explore the variation of SPS probability with different parameters and it is found that probability varies with the total number of photons in a system, the q parameter should be negative and the addition of a Photon is more suitable than subtraction for single photon source criterion.

Kazuya Takemoto, Yoshihiro Nambu, Toshiyuki Miyazawa +4 more

Advances in single-photon sources (SPSs) and single-photon detectors (SPDs) promise unique applications in the field of quantum information technology. In this paper, we report long-distance quantum key distribution (QKD) by using state-of-the-art devices: a quantum-dot SPS (QD SPS) emitting a photon in the telecom band of 1.5 μm and a superconducting nanowire SPD (SNSPD). At the distance of 100 km, we obtained the maximal secure key rate of 27.6 bps without using decoy states, which is at least threefold larger than the rate obtained in the previously reported 50-km-long QKD experiment. We also succeeded in transmitting secure keys at the rate of 0.307 bps over 120 km. This is the longest QKD distance yet reported by using known true SPSs. The ultralow multiphoton emissions of our SPS and ultralow dark count of the SNSPD contributed to this result. The experimental results demonstrate the potential applicability of QD SPSs to practical telecom QKD networks.

Matthew T. Rakher

Daniel Istrate

Moez Attia, Amor Gueddana, Rihab Chatta

In this work we address a comparison study between two kinds of Single Photon Sources (SPS). The first SPS is an Enhanced SPS (ESPS), which consists of an association between InAs/GaAs Quantum Dot (QD) and photonic crystal (PC) microcavity. The ESPS emits a single photon at 1550 nm with probability P1 around 0.7. The second SPS is the Heralded SPS (HSPS) and based on active two-dimensional PC over LiNbO3 and emits photons at 1310 nm and 1550nm. The photon at 1310 nm triggers the detection mechanism of the photon at 1550nm. The probability to obtain a HSPS at 1550 nm is closed to 0.57. Finally, we present a comparison study between ESPS and HSPS when they are used in an application of quantum communication.