In Print

A collection of my most cited research papers, and a selection of my books.

Research

The classical-quantum boundary for correlations: Discord and related measures

One of the best signatures of nonclassicality in a quantum system is the existence of correlations that have no classical counterpart. Different methods for quantifying the quantum and classical parts of correlations are amongst the more actively-studied topics of quantum information theory over the past decade. Entanglement is the most prominent of these correlations, but in many cases unentangled states exhibit nonclassical behavior too. Thus distinguishing quantum correlations other than entanglement provides a better division between the quantum and classical worlds, especially when considering mixed states. Here we review different notions of classical and quantum correlations quantified by quantum discord…

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Entanglement measures and purification procedures

We improve previously proposed conditions each measure of entanglement has to satisfy. We present a class of entanglement measures that satisfy these conditions and show that the quantum relative entropy and Bures metric generate two measures of this class. We calculate the measures of entanglement for a number of mixed two spin-1/2 systems using the quantum relative entropy, and provide an efficient numerical method to obtain the measures of entanglement in this case. In addition, we prove a number of properties of our entanglement measure that have important physical implications. We briefly explain the statistical basis of our measure of…

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Quantifying entanglement

We present conditions every measure of entanglement has to satisfy, and construct a whole class of “good” entanglement measures. The generalization of our class of entanglement measures to more than two particles is straightforward. We present a measure which has a statistical operational basis that might enable experimental determination of the quantitative degree of entanglement.

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Classical, quantum and total correlations

We discuss the problem of separating consistently the total correlations in a bipartite quantum state into a quantum and a purely classical part. A measure of classical correlations is proposed and its properties are explored.

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The Quantum Double Slit Experiment With Local Elements of Reality

We present a fully local treatment of the double slit experiment in the formalism of quantum field theory. Our exposition is predominantly pedagogical in nature and exemplifies the fact that there is an entirely local description of the quantum double slit interference that does not suffer from any supposed paradoxes usually related to the wave-particle duality. The wave-particle duality indeed vanishes in favour of the field picture in which particles should not be regarded as the primary elements of reality and only represent excitations of some specific field configurations. Our treatment is general and can be applied to any other…

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Entanglement in many-body systems

The recent interest in aspects common to quantum information and condensed matter has prompted a flory of activity at the border of these disciplines that were far distant until few years ago. Numerous interesting questions have been addressed so far. Here we review an important part of this field, the properties of the entanglement in many-body systems. We discuss the zero and finite temperature properties of entanglement in interacting spin, fermion and boson model systems. Both bipartite and multipartite entanglement will be considered. In equilibrium we show how entanglement is tightly connected to the characteristics of the phase diagram. The…

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Visit the full research archive at Arxiv

Books

Modern Foundations Of Quantum Optics
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Introductory Quantum Physics And Relativity
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Solid State Quantum Information
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Introduction to Quantum Information Science
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Decoding Reality
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From Micro to Macro
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My Blog

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Quantum Time and Cloning

I’ve recently been busy finalising a big review (300 plus references), together with Chiara Marletto, on Quantum Information methods applied to detecting…

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Pyramids, Consciousness and the Limits of Science

I’ve recently watched a great simulation of how the human hearing mechanism operates. The air vibrations generated by some disturbance eventually reach our eardrum. The ensuing vibrations of the drum perturb a small bone called the hammer which starts to move up and down.

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Quantum computational advantage and counting particles and waves

Many people take the beginning of the field of quantum computation to be a paper by Feynman titled “There is plenty of room at the bottom” (1959, but unnoticed till the early 80s).

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