New lower bounds to the output entropy of multi-mode quantum Gaussian channels

05/31/2018
by   Giacomo De Palma, et al.
0

We prove that quantum thermal Gaussian input states minimize the output entropy of the multi-mode quantum Gaussian attenuators and amplifiers that are entanglement breaking and of the multi-mode quantum Gaussian phase contravariant channels among all the input states with a given entropy. This is the first time that this property is proven for a multi-mode channel without restrictions on the input states. A striking consequence of this result is a new lower bound on the output entropy of all the multi-mode quantum Gaussian attenuators and amplifiers in terms of the input entropy. We apply this bound to determine new upper bounds to the communication rates in two different scenarios. The first is classical communication to two receivers with the quantum degraded Gaussian broadcast channel. The second is the simultaneous classical communication, quantum communication and entanglement generation or the simultaneous public classical communication, private classical communication and quantum key distribution with the Gaussian quantum-limited attenuator. In this second scenario, our bound is the first that does not rely on still unproven conjectures.

READ FULL TEXT

page 1

page 2

page 3

page 4

research
01/24/2018

Energy-constrained two-way assisted private and quantum capacities of quantum channels

With the rapid growth of quantum technologies, knowing the fundamental c...
research
02/07/2019

Entropy Bound for the Classical Capacity of a Quantum Channel Assisted by Classical Feedback

We prove that the classical capacity of an arbitrary quantum channel ass...
research
11/18/2020

Quantum Broadcast Channels with Cooperating Decoders: An Information-Theoretic Perspective on Quantum Repeaters

Communication over a quantum broadcast channel with cooperation between ...
research
01/30/2020

Kelly Betting with Quantum Payoff: a continuous variable approach

The main purpose of this study is to introduce a semi-classical model de...
research
10/29/2020

Fundamental limitations to key distillation from Gaussian states with Gaussian operations

We establish fundamental upper bounds on the amount of secret key that c...
research
07/30/2021

Fluctuation and dissipation in memoryless open quantum evolutions

Von Neumann entropy rate for open quantum systems is, in general, writte...
research
08/11/2020

Multi-User Distillation of Common Randomness and Entanglement from Quantum States

We construct new protocols for the tasks of converting noisy multipartit...

Please sign up or login with your details

Forgot password? Click here to reset