Perspective Stretching the limits of multiparticle entanglement Géza Tóth, Quantum Views 4, 30 (2020). The classification of entangled mixed states in multiparticle systems is a difficult task. Even for three-qubit pure states, six classes arise that are inequivalent under Stochastic Local Op…
Perspective Perspective on: Duality in Quantum Quenches and Classical Approximation Algorithms: Pretty Good or Very Bad Nicholas Chancellor, Quantum Views 4, 29 (2020). This paper examines both a quantum, and highly related quantum inspired algorithm based on an instantaneous quantum quench. Since this algorithm uses a transverse field (single bit flip) dri…
Perspective Geometry and quantum thermodynamics John Goold, Quantum Views 3, 28 (2019). It has been known for quite some time that equilibrium thermodynamics can be recast in a general geometric framework by associating an intrinsic metric structure [1,2]. If fluctuations are i…
Perspective Quantum measurements – yet another surprise Eliahu Cohen, Quantum Views 3, 27 (2019). When you measure a quantum system, the outcome will be one of the eigenvalues of the measured (Hermitian) operator. If you perform this measurement over an ensemble of (normalized) pure stat…
Perspective Matrix product state approximations: Bringing theory closer to practice Yichen Huang, Quantum Views 3, 26 (2019). Classical simulation of quantum many-body systems is a fundamental challenge in condensed matter physics. Part of the difficulty stems from the fact that the dimension of the Hilbert space g…
Perspective Optimal Heat-Bath Algorithmic Cooling Martí Perarnau-Llobet, Quantum Views 3, 25 (2019). Cooling is arguably the most relevant thermodynamic task for quantum science and technologies, finding countless applications ranging from the preparation of pure states for quantum computat…
Perspective How good is a positive map at detecting quantum entanglement? Ion Nechita, Quantum Views 3, 24 (2019). Since the dawn of quantum mechanics, entanglement has been a central notion of the theory [18], a very important body of work being dedicated to understanding, classifying, measuring, and ch…
Perspective Deducing entanglement from signal fluctuations Alain Sarlette, Quantum Views 3, 23 (2019). The paper by Elouard et al, 2019 [1], considers the heralded entanglement between two qubits, from a continuous-time measurement that creates this entanglement. While the process is well-kno…
Perspective Quantum channels look simpler if you squint Jonas Helsen, Quantum Views 3, 22 (2019). One of the basic tools in any quantum information theorist is the completely positive trace preserving map, or quantum channel. They provide a general framework for discussing the dynamics a…
Perspective Framework for Hamiltonian simulation and beyond: standard-form encoding, qubitization, and quantum signal processing Su Yuan, Quantum Views 3, 21 (2019). Simulating the Hamiltonian dynamics of a quantum system is one of the most promising applications of quantum computers. Indeed, the idea of quantum computers, suggested by Feynman [1] and Ma…
Perspective Quantum refrigerators – the quantum thermodynamics of cooling Bose gases Sebastian Deffner, Quantum Views 3, 20 (2019). We are living in exciting times. All around the globe national as well as international entities have founded "quantum initiatives", whose goal is the development of practical and commercial…
Perspective Simulating lossy multiphoton linear optics experiments Alex Neville, Quantum Views 3, 19 (2019). A significant research effort is being made to develop near-term quantum devices which fall short of fault-tolerance requirements and the ability to perform universal computation, but are ab…
Perspective Quantum adiabatic theory ventures into zeno dynamics Martin Fraas, Quantum Views 3, 18 (2019). Quantum adiabatic theory has been developing through a productive interplay between applications in physics and formalisation in mathematics. It originated in the work of Born and Fock [1] o…
Perspective What can we learn from trivial measurements? Marius Krumm, Quantum Views 3, 17 (2019). The discovery of quantum mechanics radically changed our understanding of the world. Today, trying to reveal the mysteries of quantum mechanics has become one of the most fruitful fields of…
Perspective The Page-Wootters mechanism 36 years on: a consistent formulation which accounts for interacting systems Mischa Woods, Quantum Views 3, 16 (2019). Do we need dynamics to explain quantum systems which change over time? In closed systems, this is indeed the case — quantum systems evolve according to the Schrödinger equation in non-relati…
Perspective The importance of being spectral Alessandro Bisio, Quantum Views 3, 15 (2019). The spectral theorem, a major result in functional analysis, states that any normal (A linear operator is normal if it is closed, densely defined, and it commutes with its adjoint.) operator…