Coherent Absorption of N00N States

Abstract

Recent results in deeply subwavelength thickness films demonstrated coherent control and logical gate operations with both classical and single photon light sources. However, quantum processing and devices typically involve more than one photon and non-trivial input quantum states. Here we experimentally investigate two-photon N00N state coherent absorption in a multilayer graphene film. Depending on the N00N state input phase, it is possible to selectively choose between single or two photon absorption of the input state in the graphene film. These results demonstrate that coherent absorption in the quantum regime exhibits unique features opening up applications in multiphoton spectroscopy and imaging. Introduction: Coherent absorption is the process by which a partially absorbing material placed in a standing wave pattern can either perfectly transmit or absorb all of the incoming light. This process occurs as a result of the coherent interaction and of the relative phase relation of the two counter-propagating waves. Originally demonstrated in thick slabs of material where the process was likened to a "time-reversed laser" [1, 2]. Coherent absorption was recently extended to deeply subwavelength thickness (2D) materials that have 50% absorption [3,4,6]. Depending on the relative phase of the incident beams, it is possible to totally absorb (or transmit) light, thus providing a method to go beyond the theoretical limit of 50% absorption in a thin film [5], and therefore provide a route to obtain optical gates that rely on absorption [7]. This process relies heavily on the relations between reflection and transmission coefficients, r and t, and absorption rate, α, of the sample [8]. A special case is found for a sub-wavelength material exhibiting precisely 50% absorption, where complete absorption (or transmission) of the energy of the two beams is possible as a result of the relation between reflection and transmission coefficients being forced to r = ±t [5]. This has been shown experimentally with classical continuous wave sources [6], ultrashort pulses [9], and has also been extended to the nonlinear regime to achieve coherent control of nonlinear wave-mixing processes [10]. However, only a few studies have looked at the quantum nature of coherent absorption. Recent experimental work has shown that a single photon also exhibits coherent perfect absorption [11,12], thus implying for example, deterministic absorption of the single photon itself. More intriguing results are expected when non-trivial quantum states interact with a lossy beamsplitter. An N=2 N00N state, (|N, 0 + e iN φ |0, N )/ √ 2 (obtained as

Plasmonic interferences of two-particle N00N states

“…Depending on the phase relation of the input N00N state, one can deterministically obtain either a single photon state or a mixture of zero and two photon states at the output. This phenomenon has been coined quantum nonlinear absorption and has been observed in a recent experiment [14]. In this setup, evidence of being in such a coherent absorption regime is given by the reminiscent single plasmon oscillations shown in figure 5.…”

“…While a lossless beamsplitter imposes a constrained phase relationship between r and t, namely r=±it, a lossy beamsplitter can be designed to exhibit any different phase relation. It has been theoretically and experimentally shown that new quantum effects arise for the case r=±t [10,13,14]. Depending on the phase relation of the input N00N state, one can deterministically obtain either a single photon state or a mixture of zero and two photon states at the output.…”

“…First, propagation losses will be revisited for plasmonic N00N states. Second, we use a lossy beamsplitter which enables us to modify the phase difference between reflection and transmission coefficients [10][11][12][13][14][15][16]. It has been shown that this effect may induce nonlinear absorption.…”

A femtosecond Raman generator for long wavelength two-photon and third harmonic generation imaging

“…35 Recently, exotic properties of lossy beam splitters, such as apparent nonlinear absorption, 36 have attracted the attention of the nanophotonics community. 29,37 As illustrated by Fig. 1(a), the interaction of two coherent beams of equal intensity on an "ideal" lossy beam splitter results in two output beams of equal intensity.…”

Quantum State Tomography with a Single Observable

“…However, such detectors often exhibit poor performance (primarily in terms of sensitivity and fall times, which affects the sampling rate), and currently the majority of quantum optics experiments are carried out with click detectors. One possible avenue for optical QST with click photodetectors is to mimic their functionality by the addition of beamsplitters 64 . However, this method introduces further losses to the system and is not scalable to larger number of channels and photons.…”