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An experimental condensed matter physicist who coauthored coherent control of a superconducting electrical circuit. Microwave pulses programmed evolution between two circuit states, while a pulsed readout circuit measured the result. The device behaved as an artificial two-level system, making a fabricated circuit a controllable carrier of quantum information.^[ref]

Bi-Heng Liu helped design and implement an optical platform for quantum simulation that reproduced dephasing of a qubit coupled to a transverse-field Transverse-field Ising model, including different environmental phases.^[ref]

A physicist working on quantum information. Affiliation recorded at publication in 2018: University of Science and Technology of China, CAS Key Laboratory of Quantum Information.^[ref]

Chuan-Feng Li co-supervised and helped design the optical dephasing experiment: a spatial light modulator shaped the photon's frequency distribution and quantum phase to control polarization dynamics.^[ref]

A physicist working on quantum information. Affiliation recorded at publication in 2018: University of Science and Technology of China, CAS Key Laboratory of Quantum Information.^[ref]

Daniel Esteve coauthored the quantronium demonstration of coherent superconducting-circuit control. Its combination of programmable microwave evolution and pulsed readout made an electrical circuit a candidate carrier of quantum information.^[ref]

Identity source: iramis.cea.fr/en/spec/gq/membres-gq-en/

Guang-Can Guo co-supervised and helped design a photon-based dephasing simulator, using controlled initial polarization–frequency correlations to investigate open quantum system dynamics.^[ref]

A physicist working on quantum information. Affiliation recorded at publication in 2018: University of Science and Technology of China, CAS Key Laboratory of Quantum Information.^[ref]

Matteo G. A. Paris is a theoretical physicist working on quantum information, quantum optics and quantum measurement. His article Quantum estimation for quantum technology by Matteo G. A. Paris explains how to estimate quantities encoded in a quantum state when a direct measurement of the desired parameter is unavailable.

The treatment uses the symmetric logarithmic derivative and Quantum Fisher information to bound attainable precision and compare measurement strategies. It connects the choice of measurement with statistical estimation, rather than assuming that repeated observations automatically achieve the best possible accuracy.^[ref]

Institutional profile: www.unimi.it/it/ugov/person/matteo-paris.

An experimental optical physicist who coauthored a bright source of polarization-entangled photon pairs in 1995. Noncollinear type-II spontaneous parametric down-conversion generated the pairs, while compensation of distinguishability allowed strong polarization entanglement. A source of this kind supplies repeatable inputs for Bell tests and experiments in quantum information.^[ref]

Quantum computing processes quantum information through controlled physical transformations and quantum measurements. In the quantum circuit model, an initial quantum state evolves through quantum gates, and the Born rule predicts the final outcome probabilities. Quantum interference makes the relative quantum phases of amplitudes computationally useful. David Deutsch's 1985 paper developed a model of universal quantum computation.^[ref]

A one-qubit example shows why amplitudes matter. Starting from $|0⟩$, a Hadamard gate gives $(|0⟩+|1⟩)/\sqrt{2}$; a second Hadamard gate returns $|0⟩$. Insert a Pauli Z gate between the two Hadamard gates and the final state is instead $|1⟩$: the intermediate relative sign changes how amplitudes combine. Measuring the intermediate state alone would give equal probabilities in both cases. A useful quantum algorithm arranges such transformations to make information about the required answer accessible through the final quantum measurement.

Quantum information science studies the storage, processing and transmission of quantum information, including the physical implementation of the tasks described by quantum information theory.

Quantum theory supplies a common language for quantum mechanics, measurement in quantum mechanics, and quantum information: prepare a quantum state, transform it, and ask which experimental outcomes occur. In a finite-dimensional idealization, a pure state is a normalized vector of complex numbers. Its entries are probability amplitudes; the Born rule turns their squared magnitudes into probabilities. Between measurements, an isolated system evolves by a unitary operator, preserving its norm and inner products. A quantum circuit makes this evolution explicit as a sequence of quantum gates.

The extra information carried by quantum phases is essential. Relative quantum phases affect how probability amplitudes add when different contributions reach the same output. Their interference can enhance one outcome and cancel another. A global phase, multiplying the entire quantum state by the same complex factor of magnitude one, changes neither these relative phases nor observable predictions. The Hadamard gate below provides a small experiment in which this distinction becomes a deterministic change of output.

Quantum coherence describes this capacity to interfere relative to a specified orthonormal basis. In a density matrix, it appears in off-diagonal entries; a diagonal mixed state retains the populations but lacks that basis coherence. Thus matching the probabilities of one measurement need not match the predictions of a later experiment. Baumgratz, Cramer, and Plenio made this basis-dependent viewpoint precise in their resource framework for quantum coherence. ^[ref].

This makes quantum information an operational question: which distinctions can a preparation, an available unitary operator, and measurement in quantum mechanics reveal? Amplitude amplification illustrates how carefully arranged interference converts a weakly represented answer into a likely observable result. Preserving the relevant quantum coherence throughout the computation is part of the physical task. ^[ref].

Sabrina Maniscalco co-supervised the theoretical analysis of an optical dephasing simulator, connecting controlled polarization–frequency preparation with the dynamics of an open quantum system.^[ref]

A physicist working on quantum information. Affiliation recorded at publication in 2018: University of Turku, Turku Centre for Quantum Physics; Aalto University, Department of Applied Physics.^[ref]

Yong-Nan Sun helped design and implement a photon-based dephasing experiment in which controlled frequency distributions and quantum phases determine the evolution of a polarization qubit.^[ref]

A physicist working on quantum information. Affiliation recorded at publication in 2018: University of Science and Technology of China, CAS Key Laboratory of Quantum Information.^[ref]

Zhao-Di Liu helped design and implement an optical dephasing simulator, controlling a photon's initial polarization–frequency quantum state to engineer the subsequent loss and revival of quantum coherence.^[ref]

A physicist working on quantum information. Affiliation recorded at publication in 2018: University of Science and Technology of China, CAS Key Laboratory of Quantum Information.^[ref]