Quantum Estimation Methods for Quantum Illumination

Abstract

Quantum illumination consists in shining quantum light on a target region immersed in a bright thermal bath with the aim of detecting the presence of a possible low-reflective object. If the signal is entangled with the receiver, then a suitable choice of the measurement offers a gain with respect to the optimal classical protocol employing coherent states. Here, we tackle this detection problem by using quantum estimation techniques to measure the reflectivity parameter of the object, showing an enhancement in the signal-to-noise ratio up to 3 dB with respect to the classical case when implementing only local measurements. Our approach employs the quantum Fisher information to provide an upper bound for the error probability, supplies the concrete estimator saturating the bound, and extends the quantum illumination protocol to non-Gaussian states. As an example, we show how Schrödinger's cat states may be used for quantum illumination.

Imaging through noise with quantum illumination

“…Quantum illumination has applications in the context of quantum information protocol such as secure communication [3,4] where it secures communication against passive eavesdropping techniques that take advantage of noise and losses. The protocol has also been proposed to be useful for detecting the presence of a target object embedded within a noisy background, despite environmental perturbations and losses destroying the initial entanglement [5,6,7].In 2013, Lopaeva et al performed an experimental demonstration of the quantum illumination principle, to determine the presence or absence of a semi-transparent object, by exploiting intensity correlations of a quantum origin in the presence of thermal light [8]. Additionally, a quantum illumination protocol has been experimentally demonstrated in the microwave domain [9] and a further demonstration in which joint detection of the signal and idler is not required [10].…”

Relativistic motion enhanced quantum estimation of $$\kappa $$ κ -deformation of spacetime

“…With the application of QET, one can estimate the parameter of interest with a higher precision which is beyond the standard classical limits [37]. Recently, this theory has been successfully applied to a wide range of metrological problems [38], relativistic quantum field [39][40][41][42][43][44][45], quantum illumination [46], biology [47], the experiments with photons [48,49] and trapped ions [50,51], and so on. Besides, to enhance the relevant estimation, different ways, such as using of quantum entanglement, feedback control, and nonlinear dynamics, have been explored [52][53][54][55][56][57][58].…”

Quantum illumination assistant with error-correcting codes

“…One of the major applications to enhance the ability of target recognition is quantum illumination [4][5][6][7][8][9], which is the most known protocol for bosonic quantum sensing [10]. Quantum illumination provides us with a potential platform to detect the low-reflectivity object embedded in a bright environment, and it is more efficiently than the way by using classical resources [5,11,12]. Since the pioneering work proposed by Lloyd [4] and its Gaussian version [6,9], many experimental and theoretical schemes have been proposed [13,14], such as quantum illumination in composite optomechanical system [5,15], discrete variable quantum illumination with ancillary degrees of freedom [16], quantum illumination unveils cloaking [14], and quantum illumination based on asymmetric hypothesis testing [17,18].…”

“…This means the lower error probability requires the higher dimension of entangled state [4], which pose a great challenge to the experimental implementation. Various schemes have been proposed to improve the feasibility of experiment, including quantum illumination with Gaussian state entanglement [6], quantum illumination combined with quantum estimation methods [11], and so on. Most recently, a fundamental lower bound of error probability of quantum illumination for both discrete variable [19] and continuous variable [20] systems have been reported.…”