Performance of a temporally multiplexed single-photon source with imperfect devices

Abstract

Scalable photonic quantum technologies require highly efficient sources of single photons on demand. Although much progress has been done in the field within the last decade, the requirements impose stringent conditions on the efficiency of such devices. One of the most promising approaches is to multiplex a single or several heralded photon sources into temporal modes. In this work we analyze a specific proposal to synchronize photons from a continuous source with an external reference clock using imperfect optical switches, which necessarily degrade the ideal behavior of the devised arrangement. The performance of the source as a sub-poissonian light emitter is studied taking into account losses in the multiplexing arrangement, detector efficiency and dark counts. We estimate a fivefold increase in the single photon probability achieved for 0.5 dB loss switches.Keywords Single Photon Source · Temporal multiplexing · Heralded Photons 1 IntroductionOne of the key requirements for building a quantum computing device, a quantum processor, or even to physically realize a quantum communication protocol, is a system that can encode quantum information. The optical photon is an attractive physical system for en-

Spatially multiplexed single-photon sources based on incomplete binary-tree multiplexers

“…Poissonian distribution is valid for multimode SPDC or SFWM processes, that is, for weaker spectral filtering [11,14,[39][40][41][42][43]. Assuming this distribution makes it possible to compare our results with the ones presented in a significant part of the literature related to SPS, which were also obtained for Poissonian distribution [9,10,16,17,27,[36][37][38]. The formula for the conditional probability 𝑃 (𝐷) ( 𝑗 |𝑙) can be obtained as…”

“…The inherent probabilistic nature of the photon pair generation in these nonlinear sources results in the occasional occurrence of multiphoton events in the pair generation. This detrimental effect can be reduced by various multiplexing techniques such as spatial multiplexing [8][9][10][11][12][13][14] and time multiplexing [15][16][17][18][19][20][21][22][23][24][25][26][27] where heralded photons generated in a set of multiplexed units realized in space or in time are rerouted to a single output mode by a switching system. In multiplexed SPSs, the multi-photon noise can be suppressed by keeping the mean photon number of the generated photon pairs low in a multiplexed unit, while the high probability of successful heralding in the whole system can be guaranteed by the use of several multiplexed units.…”

Scheme for sub-shot-noise transmission measurement using a time-multiplexed single-photon source

“…Active switching of this stages allows for compensation of a temporal mismatch (between the photon and the clock) up to T = (2 m − 1) t. A detailed description of the source can be found in [40]. The probability mass function of emitting i photons of this source, P (m) b (i), assuming no dark counts at the heralding detector was introduced and discussed in [54]:…”

“…When using NR detectors, the measured random variable k is the detected number of photons. For the three different sources considered in this work, the emission probability distribution of i photons is Poissonian in the coherent case P (i, α), sub-Poissonian in BinMux-SP with m delay stages P (m) b (i) [54], and a perfect number state-with null variance-in the singlephoton Fock case. The inefficiency of the detection process combines the emission distribution with an additional binomial distribution in each case to describe the statistics of the random variable k.…”

“…In this work, we propose the use of a specific engineered single-photon-pulsed source [40,54] that relies on the correlations present in a photon pair SPDC source and on a binary-length division time-multiplexing network as the input of a direct-type transmission measurement. We compare its performance both with a weak coherent pulse source with Poissonian statistics (a "classical" experiment) and an ideal "photon gun," that is, a deterministic source that emits a single photon per pulse.…”