# The Squashed Entanglement of a Quantum Channel

@article{Takeoka2014TheSE, title={The Squashed Entanglement of a Quantum Channel}, author={Masahiro Takeoka and Saikat Guha and Mark M. Wilde}, journal={IEEE Transactions on Information Theory}, year={2014}, volume={60}, pages={4987-4998} }

This paper defines the squashed entanglement of a quantum channel as the maximum squashed entanglement that can be registered by a sender and receiver at the input and output of a quantum channel, respectively. A new subadditivity inequality for the original squashed entanglement measure of Christandl and Winter leads to the conclusion that the squashed entanglement of a quantum channel is an additive function of a tensor product of any two quantum channels. More importantly, this new…

## 89 Citations

Squashed entanglement and the two-way assisted capacities of a quantum channel

- Physics2014 IEEE International Symposium on Information Theory
- 2014

A new subadditivity inequality for the original squashedEntanglement measure of Christandl and Winter leads to the conclusion that the squashed entanglement of a quantum channel is an additive function of a tensor product of any two quantum channels.

Bounds on Entanglement Distillation and Secret Key Agreement for Quantum Broadcast Channels

- Computer Science, PhysicsIEEE Transactions on Information Theory
- 2016

This paper employs multipartite generalizations of the squashed entanglement to constrain the rates at which secret key and entanglements can be generated between any subset of the users of such a channel, along the way developing several new properties of these measures.

Amortized entanglement of a quantum channel and approximately teleportation-simulable channels

- Computer ScienceArXiv
- 2017

Many of the concepts in the paper are generalized to the setting of general resource theories, defining the amortized resourcefulness of a channel and the notion of ν-freely-simulable channels, connecting these concepts in an operational way as well.

Assessing the performance of quantum repeaters for all phase-insensitive Gaussian bosonic channels

- Physics
- 2015

One of the most sought-after goals in experimental quantum communication is the implementation of a quantum repeater. The performance of quantum repeaters can be assessed by comparing the attained…

Squashed entanglement and approximate private states

- PhysicsQuantum Inf. Process.
- 2016

This paper simplifies proofs that the squashed entanglement is an upper bound on distillable key for finite-dimensional quantum systems and solidifies such proofs for infinite-dimensionalquantum systems.

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

- Physics, Computer SciencePhysical Review A
- 2018

It is proved that a thermal state maximizes a relaxation of the squashed entanglement of all phase-insensitive, single-mode input bosonic Gaussian channels, generalizing results from prior work and proving that a variation of the method introduced in Goodenough et al. leads to improved upper bounds on the energy-constrained secret-key-agreement capacity of a bosonic thermal channel.

Amortization does not enhance the max-Rains information of a quantum channel

- Computer Science, PhysicsArXiv
- 2017

The main technical result is that amortization does not enhance the entanglement of an arbitrary quantum channel, whenEntanglement is quantified by the max-Rains relative entropy.

Pursuing the Fundamental Limits for Quantum Communication

- Computer Science, PhysicsIEEE Transactions on Information Theory
- 2021

Improved upper bounds to the quantum and private capacities for fundamental quantum channels of interest in quantum information are established, some of which are also the sources of noise in superconducting quantum computing.

Optimizing the fundamental limits for quantum and private communication

- Computer ScienceArXiv
- 2019

Improved upper bounds to the quantum and private capacities for fundamental quantum channels of great interest in quantum information are established, some of which are also the sources of noise in superconducting quantum computing.

Entropic Bounds on Two-Way Assisted Secret-Key Agreement Capacities of Quantum Channels

- Computer Science
- 2018

This work defines the communication task of establishing a secret key over a quantum channel subject to an energy constraint on the input state and while allowing for unlimited local operations and classical communication between a sender and receiver, and defines the broadcast amplitude damping channel.

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