Abstract
Single photon detectors have historically consisted of macroscopic-sized materials but recent experimental and theoretical progress suggests new approaches based on nanoscale and molecular electronics. Here we present a theoretical study of photodetection in a system composed of a quantum electronic transport channel functionalized by a photon absorber. Notably, the photon field, absorption process, transduction mechanism, and measurement process are all treated as part of one fully-coupled quantum system, with explicit interactions. Using non-equilibrium, time-dependent quantum transport simulations, we reveal the unique temporal signatures of the single photon detection process, and show that the system can be described using optical Bloch equations, with a new non-linearity as a consequence of time-dependent detuning caused by the backaction from the transport channel via the dynamical Stark effect. We compute the photodetector signal-to-noise ratio and demonstrate that single photon detection at high count rate is possible for realistic parameters by exploiting a novel non-equilibrium control of backaction.
Highlights
Single-photon detection has recently played a key role in addressing long-standing basic physics questions such as Bell’s theorem [1] and quantum teleportation [2], as well as enabling potential new approaches for quantum information science [3]
To study the system dynamics, we employ a nonequilibrium Green’s function (NEGF) formalism based on the equation of motion for the one-particle Green’s function [27], treating the Coulomb interaction inside the functionalized transport channel at the mean-field Hartree-Fock level
We reveal the complex dynamics of such systems, and identify nonequilibrium electronic transport as a mechanism to control back-action
Summary
Single-photon detection has recently played a key role in addressing long-standing basic physics questions such as Bell’s theorem [1] and quantum teleportation [2], as well as enabling potential new approaches for quantum information science [3]. One avenue is to consider arrays of nanometer scale photodetectors instead of the existing bulk detectors In such arrays, each element simultaneously interacts with the photon field and outputs a signal, providing advantages for performance and photon-number resolution as determined from general considerations [4]. Each element simultaneously interacts with the photon field and outputs a signal, providing advantages for performance and photon-number resolution as determined from general considerations [4] To realize such arrays, it is critical to identify physical device elements that can satisfy the stringent constraints. Carbon nanotubes (CNTs) functionalized with molecules have been explored [6,7,8], as well as photoswitched molecular electronic systems [9] These nano/molecular systems are promising as array elements but such systems in the presence of lightmatter interactions are out of equilibrium and require careful considerations of their properties. Our approach is used to demonstrate a high signal-to-noise ratio for single-photon detection at high count rate (∼GHz)
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