Professor Artur Ekert FRS: Publications

From quantum code-making to quantum code-breaking

(1998) 195-214

Quantum computation: theory and experiment - Discussion held 5 and 6 November 1997 - Preface

PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES 356:1743 (1998) 1715-1715

Authors:

A Ekert, R Jozsa, R Penrose

Quantum privacy amplification and the security of quantum cryptography over noisy channels (vol 77, pg 2818, 1996)

PHYSICAL REVIEW LETTERS 80:9 (1998) 2022-2022

Authors:

D Deutsch, A Ekert, R Jozsa, C Macchiavello, S Popescu, A Sanpera

Quantum computing with controlled-NOT and few qubits

Philosophical Transactions of the Royal Society A Mathematical Physical and Engineering Sciences 355:1733 (1997) 2259-2266

Authors:

D Bruss, A Ekert, SF Huelga, JW Pan, A Zeilinger

Abstract:

We describe simple quantum networks which allow us to prepare, manipulate and measure quantum entanglement of few qubits.

Optimal universal quantum cloning and state estimation

ArXiv quant-ph/9712019 (1997)

Authors:

D Bruss, A Ekert, C Macchiavello

Abstract:

We derive a tight upper bound for the fidelity of a universal N to M qubit cloner, valid for any M \geq N, where the output of the cloner is required to be 91̽��ed on the symmetric subspace. Our proof is based on the concatenation of two cloners and the connection between quantum cloning and quantum state estimation. We generalise the operation of a quantum cloner to mixed and/or entangled input qubits described by a density matrix 91̽��ed on the symmetric subspace of the constituent qubits. We also extend the validity of optimal state estimation methods to inputs of this kind.

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