Erratum: Ultimate Precision of Adaptive Noise Estimation [Phys. Rev. Lett. 118 , 100502 (2017)]

Quantum illumination is a technique for detecting the presence of a target in a noisy environment by means of a quantum probe. We prove that the two-mode squeezed vacuum state is the optimal probe for quantum illumination in the scenario of asymmetric discrimination, where the goal is to minimize the decay rate of the probability of a false positive with a given probability of a false negative. Quantum illumination with two-mode squeezed vacuum states offers a 6 dB advantage in the error probability exponent compared to illumination with coherent states. Whether more advanced quantum illumination strategies may offer further improvements had been a longstanding open question. Our fundamental result proves that nothing can be gained by considering more exotic quantum states, such as e.g. multi-mode entangled states. Our proof is based on a new fundamental entropic inequality for the noisy quantum Gaussian attenuators. We also prove that without access to a quantum memory, the optimal probes for quantum illumination are the coherent states.

Section: Discussionmentioning

confidence: 88%

Minimum error probability of quantum illumination

Palma

Borregaard

2018

“…This consists of a technique, dubbed "teleportation stretching", which reduces an adaptive protocol (with any communication task) into a much simpler block-type protocol. More recently, this technique has been extended to simplify adaptive protocols of quantum metrology and quantum channel discrimination [48]. The first step of the technique is the LOCC simulation of a quantum channel.…”

Section: Remarkmentioning

confidence: 99%

General bounds for sender-receiver capacities in multipoint quantum communications

Laurenza

Pirandola

2017

Self Cite

We investigate the maximum rates for transmitting quantum information, distilling entanglement and distributing secret keys between a sender and a receiver in a multipoint communication scenario, with the assistance of unlimited two-way classical communication involving all parties. First we consider the case where a sender communicates with an arbitrary number of receivers, so called quantum broadcast channel. Here we also provide a simple analysis in the bosonic setting where we consider quantum broadcasting through a sequence of beamsplitters. Then, we consider the opposite case where an arbitrary number of senders communicate with a single receiver, so called quantum multiple-access channel. Finally, we study the general case of all-in-all quantum communication where an arbitrary number of senders communicate with an arbitrary number of receivers. Since our bounds are formulated for quantum systems of arbitrary dimension, they can be applied to many different physical scenarios involving multipoint quantum communication.

“…where ρ ++ , ρ −− are the populations of |± ≡ (| ↑ ± | ↓ )/ √ 2 in the initial state ρ 0 and the inequality is saturated at |ρ +− | 2 = ρ ++ ρ −− and ρ ++ = ρ −− = 1/2. Equation (35) is also the ultimate precision bound [102] for adaptive estimation of the dephasing rate without MQT. Comparing Eq.…”

Section: Estimation Of γmentioning

confidence: 99%

Improving quantum parameter estimation by monitoring quantum trajectories

Pang

Chen

et al. 2019

Quantum-enhanced parameter estimation has widespread applications in many fields. An important issue is to protect the estimation precision against the noise-induced decoherence. Here we develop a general theoretical framework for improving the precision for estimating an arbitrary parameter by monitoring the noise-induced quantum trajectorie (MQT) and establish its connections to the purification-based approach to quantum parameter estimation. MQT can be achieved in two ways: (i) Any quantum trajectories can be monitored by directly monitoring the environment, which is experimentally challenging for realistic noises; (ii) Certain quantum trajectories can also be monitored by frequently measuring the quantum probe alone via ancilla-assisted encoding and error detection. This establishes an interesting connection between MQT and the full quantum error correction protocol. Application of MQT to estimate the level splitting and decoherence rate of a spin-1/2 under typical decoherence channels demonstrate that it can avoid the long-time exponential loss of the estimation precision and, in special cases, recover the Heisenberg scaling.