Quantum

Paper

Optimized Entanglement Purification

Stefan Krastanov, Victor V. Albert, and Liang Jiang,

Quantum 3, 123 (2019).

We investigate novel protocols for entanglement purification of qubit Bell pairs. Employing genetic algorithms for the design of the purification circuit, we obtain shorter circuits achievin…

Paper

An efficient high dimensional quantum Schur transform

Hari Krovi,

Quantum 3, 122 (2019).

The Schur transform is a unitary operator that block diagonalizes the action of the symmetric and unitary groups on an $n$ fold tensor product $V^{\otimes n}$ of a vector space $V$ of dimens…

Paper

Thermodynamics as a Consequence of Information Conservation

Manabendra Nath Bera, Arnau Riera, Maciej Lewenstein, Zahra Baghali Khanian, and Andreas Winter,

Quantum 3, 121 (2019).

Thermodynamics and information have intricate interrelations. Often thermodynamics is considered to be the logical premise to justify that $\textit{information is physical}$ – through Landau…

Paper

Fault-tolerant gates via homological product codes

Tomas Jochym-O’Connor,

Quantum 3, 120 (2019).

A method for the implementation of a universal set of fault-tolerant logical gates is presented using homological product codes. In particular, it is shown that one can fault-tolerantly map…

Paper

On the classification of two-qubit group orbits and the use of coarse-grained ‘shape’ as a superselection property

Thomas Hebdige and David Jennings,

Quantum 3, 119 (2019).

Recently a complete set of entropic conditions has been derived for the interconversion structure of states under quantum operations that respect a specified symmetry action, however the cor…

Paper

All macroscopic quantum states are fragile and hard to prepare

Andrea López-Incera, Pavel Sekatski, and Wolfgang Dür,

Quantum 3, 118 (2019).

We study the effect of local decoherence on arbitrary quantum states. Adapting techniques developed in quantum metrology, we show that the action of generic local noise processes –though ar…

Paper

POVMs are equivalent to projections for perfect state exclusion of three pure states in three dimensions

Abel Molina,

Quantum 3, 117 (2019).

Performing perfect/conclusive quantum state exclusion means to be able to discard with certainty at least one out of $n$ possible quantum state preparations by performing a measurement of th…

Paper

Optimising Matrix Product State Simulations of Shor’s Algorithm

Aidan Dang, Charles D. Hill, and Lloyd C. L. Hollenberg,

Quantum 3, 116 (2019).

We detail techniques to optimise high-level classical simulations of Shor's quantum factoring algorithm. Chief among these is to examine the entangling properties of the circuit and to effec…

Paper

Locally Maximally Entangled States of Multipart Quantum Systems

Jim Bryan, Samuel Leutheusser, Zinovy Reichstein, and Mark Van Raamsdonk,

Quantum 3, 115 (2019).

For a multipart quantum system, a locally maximally entangled (LME) state is one where each elementary subsystem is maximally entangled with its complement. This paper is a sequel to~[J. Bry…

Paper

Exact Ising model simulation on a quantum computer

Alba Cervera-Lierta,

Quantum 2, 114 (2018).

We present an exact simulation of a one-dimensional transverse Ising spin chain with a quantum computer. We construct an efficient quantum circuit that diagonalizes the Ising Hamiltonian and…

Paper

Bound entangled states fit for robust experimental verification

Gael Sentís, Johannes N. Greiner, Jiangwei Shang, Jens Siewert, and Matthias Kleinmann,

Quantum 2, 113 (2018).

Preparing and certifying bound entangled states in the laboratory is an intrinsically hard task, due to both the fact that they typically form narrow regions in state space, and that a certi…

Paper

Quantum Interference of Force

Raul Corrêa, Marina F. B. Cenni, and Pablo L. Saldanha,

Quantum 2, 112 (2018).

We show that a quantum particle subjected to a positive force in one path of a Mach-Zehnder interferometer and a null force in the other path may receive a negative average momentum transfer…

Paper

Experimental investigation of high-dimensional quantum key distribution protocols with twisted photons

Frédéric Bouchard, Khabat Heshami, Duncan England, Robert Fickler, Robert W. Boyd, Berthold-Georg Englert, Luis L. Sánchez-Soto, and Ebrahim Karimi,

Quantum 2, 111 (2018).

Quantum key distribution is on the verge of real world applications, where perfectly secure information can be distributed among multiple parties. Several quantum cryptographic protocols hav…

Paper

Restoring Heisenberg scaling in noisy quantum metrology by monitoring the environment

Francesco Albarelli, Matteo A. C. Rossi, Dario Tamascelli, and Marco G. Genoni,

Quantum 2, 110 (2018).

We study quantum frequency estimation for $N$ qubits subjected to independent Markovian noise, via strategies based on time-continuous monitoring of the environment. Both physical intuition…

Paper

Hallmarking quantum states: unified framework for coherence and correlations

Gian Luca Giorgi and Roberta Zambrini,

Quantum 2, 109 (2018).

Quantum coherence and distributed correlations among subparties are often considered as separate, although operationally linked to each other, properties of a quantum state. Here, we propose…

Paper

Beyond the thermodynamic limit: finite-size corrections to state interconversion rates

Christopher T. Chubb, Marco Tomamichel, and Kamil Korzekwa,

Quantum 2, 108 (2018).

Thermodynamics is traditionally constrained to the study of macroscopic systems whose energy fluctuations are negligible compared to their average energy. Here, we push beyond this thermodyn…

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