Nonzero temperature effects on antibunched photons emitted by a quantum point contact out of equilibrium

TL;DR

This paper extends the theory of photon statistics emitted by a quantum point contact to nonzero temperatures, revealing how thermal fluctuations influence photon antibunching and bunching behavior.

Contribution

It introduces a nonzero temperature extension to the existing zero-temperature theory, highlighting the role of detector bandwidth and thermal effects on photon antibunching.

Findings

Photon antibunching persists below a critical temperature T_c

Thermal fluctuations hinder narrow-band detection of antibunching

Crossover from antibunched to bunched photons occurs at T_c

Abstract

Electrical current fluctuations in a single-channel quantum point contact can produce photons (at frequency omega close to the applied voltage V x e/hbar) which inherit the sub-Poissonian statistics of the electrons. We extend the existing zero-temperature theory of the photostatistics to nonzero temperature T. The Fano factor F (the ratio of the variance and the average photocount) is <1 for T<T_c (antibunched photons) and >1 for T>T_c (bunched photons). The crossover temperature T_c ~ Deltaomega x hbar/k_B is set by the band width Deltaomega of the detector, even if hbar x Deltaomega << eV. This implies that narrow-band detection of photon antibunching is hindered by thermal fluctuations even in the low-temperature regime where thermal electron noise is negligible relative to shot noise.