89 results found
Petiziol F, Dive B, Carretta S, et al., 2019, Accelerating adiabatic protocols for entangling two qubits in circuit QED, PHYSICAL REVIEW A, Vol: 99, ISSN: 2469-9926
Holmes Z, Weidt S, Jennings D, et al., 2019, Coherent fluctuation relations: from the abstract to the concrete, Quantum, Vol: 3, ISSN: 2521-327X
Recent studies using the quantum information theoretic approach to thermodynamics show that the presence of coherence in quantum systems generates corrections to classical fluctuation theorems. To explicate the physical origins and implications of such corrections, we here convert an abstract framework of an autonomous quantum Crooks relation into quantum Crooks equalities for well-known coherent, squeezed and cat states. We further provide a proposal for a concrete experimental scenario to test these equalities. Our scheme consists of the autonomous evolution of a trapped ion and uses a position dependent AC Stark shift.
Walker BT, Flatten LC, Hesten HJ, et al., 2018, Driven-dissipative non-equilibrium Bose-Einstein condensation of less than ten photons, Nature Physics, Vol: 14, Pages: 1173-1177+, ISSN: 1745-2473
In a Bose–Einstein condensate, bosons condense in the lowest-energy mode available and exhibit high coherence. Quantum condensation is inherently a multimode phenomenon, yet understanding of the condensation transition in the macroscopic limit is hampered by the difficulty in resolving populations of individual modes and the coherences between them. Here, we report non-equilibrium Bose–Einstein condensation of 7 ± 2 photons in a sculpted dye-filled microcavity, where the extremely small particle number and large mode spacing of the condensate allow us to measure occupancies and coherences of the individual energy levels of the bosonic field. Coherence of the individual modes is found to generally increase with increasing photon number. However, at the break-down of thermal equilibrium we observe phase transitions to a multimode condensate regime wherein coherence unexpectedly decreases with increasing population, suggesting the presence of strong intermode phase or number correlations despite the absence of a direct nonlinearity. Experiments are well-matched to a detailed non-equilibrium model. We find that microlaser and Bose–Einstein statistics each describe complementary parts of our data and are limits of our model in appropriate regimes, providing elements to inform the debate on the differences between the two concepts1,2.
Tranter A, Love PJ, Mintert F, et al., 2018, A Comparison of the Bravyi-Kitaev and Jordan-Wigner Transformations for the Quantum Simulation of Quantum Chemistry, JOURNAL OF CHEMICAL THEORY AND COMPUTATION, Vol: 14, Pages: 5617-5630, ISSN: 1549-9618
Petiziol F, Dive B, Mintert F, et al., 2018, Fast adiabatic evolution by oscillating initial Hamiltonians, PHYSICAL REVIEW A, Vol: 98, ISSN: 2469-9926
Verdeny A, Puig J, Mintert F, 2018, Quasi-Periodically Driven Quantum Systems, ZEITSCHRIFT FUR NATURFORSCHUNG SECTION A-A JOURNAL OF PHYSICAL SCIENCES, Vol: 71, Pages: 897-907, ISSN: 0932-0784
Latmiral L, Mintert F, 2018, Deterministic preparation of highly non-classical macroscopic quantum states, npj Quantum Information, Vol: 4, ISSN: 2056-6387
We present a scheme to deterministically prepare non-classical quantum states of a massive mirror including highly non-Gaussian states exhibiting sizeable negativity of the Wigner function. This is achieved by exploiting the non-linear light–matter interaction in an optomechanical cavity by driving the system with optimally designed frequency patterns. Our scheme reveals to be resilient against mechanical and optical damping, as well as mechanical thermal noise and imperfections in the driving scheme. Our proposal thus opens a promising route for table-top experiments to explore and exploit macroscopic quantum phenomena.
Dive B, Pitchford A, Burgarth D, et al., 2018, In situ upgrade of quantum simulators to universal computers, Quantum, Vol: 2, Pages: 80-80, ISSN: 2521-327X
Quantum simulators, machines that can replicate the dynamics of quantum systems, are being built as useful devices and are seen as a stepping stone to universal quantum computers. A key difference between the two is that computers have the ability to perform the logic gates that make up algorithms. We propose a method for learning how to construct these gates efficiently by using the simulator to perform optimal control on itself. This bypasses two major problems of purely classical approaches to the control problem: the need to have an accurate model of the system, and a classical computer more powerful than the quantum one to carry out the required simulations. Strong evidence that the scheme scales polynomially in the number of qubits, for systems of up to 9 qubits with Ising interactions, is presented from numerical simulations carried out in different topologies. This suggests that this in situ approach is a practical way of upgrading quantum simulators to computers.
Hesten HJ, Nyman RA, Mintert F, 2018, Decondensation in Nonequilibrium Photonic Condensates: When Less Is More, PHYSICAL REVIEW LETTERS, Vol: 120, ISSN: 0031-9007
Kaufman AM, Tichy MC, Mintert F, et al., 2018, The Hong-Ou-Mandel Effect With Atoms, ADVANCES IN ATOMIC, MOLECULAR, AND OPTICAL PHYSICS, VOL 67, Editors: Arimondo, DiMauro, Yelin, Publisher: ELSEVIER ACADEMIC PRESS INC, Pages: 377-427
Krimer DO, Hartl B, Mintert F, et al., 2017, Optimal control of non-Markovian dynamics in a single-mode cavity strongly coupled to an inhomogeneously broadened spin ensemble, PHYSICAL REVIEW A, Vol: 96, ISSN: 2469-9926
Quantum optics is the study of the intrinsically quantum properties of light. During the second part of the 20th century experimental and theoretical progress developed together; nowadays quantum optics provides a testbed of many fundamental aspects of quantum mechanics such as coherence and quantum entanglement. Quantum optics helped trigger, both directly and indirectly, the birth of quantum technologies, whose aim is to harness non-classical quantum effects in applications from quantum key distribution to quantum computing. Quantum light remains at the heart of many of the most promising and potentially transformative quantum technologies. In this review, we celebrate the work of Sir Peter Knight and present an overview of the development of quantum optics and its impact on quantum technologies research. We describe the core theoretical tools developed to express and study the quantum properties of light, the key experimental approaches used to control, manipulate and measure such properties and their application in quantum simulation, and quantum computing.
Newman D, Mintert F, Nazir A, 2017, Performance of a quantum heat engine at strong reservoir coupling, PHYSICAL REVIEW E, Vol: 95, ISSN: 2470-0045
Witt B, Rudnicki L, Tanimura Y, et al., 2017, Exploring complete positivity in hierarchy equationsof motion, New Journal of Physics, Vol: 19, ISSN: 1367-2630
We derive a purely algebraic framework for the identi cation of hierarchyequations of motion that induce completely positive dynamics and demonstrate the applicability of our approach with several examples. We nd bounds on the violation of complete positivity for microscopically derived hierarchy equations of motion and construct well-behaved phenomenological models with strongly non-Markovian revivals of quantum coherence.
Haddadfarshi F, Mintert, 2016, High fidelity quantum gates of trapped ions mediated by a dissipative bus mode, New Journal of Physics, Vol: 18, ISSN: 1367-2630
We describe entangling quantum gates for trapped ions mediated bya dissipative bus mode and show that suitably designed, polychromatic controlpulses decrease ion-phonon entanglement substantially while maintaining the mediatedinteraction. In particular for multi-qubit gates this yields a signi cant improvement ingate performance.
Haddadfarshi F, Mintert F, 2016, High fidelity quantum gates of trapped ions in the presence of motional heating, NEW JOURNAL OF PHYSICS, Vol: 18, ISSN: 1367-2630
Nyman RA, Marelic J, Zajiczek LF, et al., 2016, Spatiotemporal coherence of non-equilibrium multimode photon condensates, New Journal of Physics, Vol: 18, ISSN: 1367-2630
We report on the observation of quantum coherence of Bose–Einstein condensed photons in an optically pumped, dye-filled microcavity. We find that coherence is long-range in space and time above condensation threshold, but short-range below threshold, compatible with thermal-equilibrium theory. Far above threshold, the condensate is no longer at thermal equilibrium and is fragmented over non-degenerate, spatially overlapping modes. A microscopic theory including cavity loss, molecular structure and relaxation shows that this multimode condensation is similar to multimode lasing induced by imperfect gain clamping.
Dive B, Burgarth D, Mintert F, 2016, Isotropy and control of dissipative quantum dynamics, PHYSICAL REVIEW A, Vol: 94, ISSN: 2469-9926
Verdeny A, Mintert F, 2015, Tunable Chern insulator with optimally shaken lattices, PHYSICAL REVIEW A, Vol: 92, ISSN: 1050-2947
von Prillwitz K, Rudnicki L, Mintert F, 2015, Contrast in multipath interference and quantum coherence, PHYSICAL REVIEW A, Vol: 92, ISSN: 1050-2947
Noebauer T, Angerer A, Bartels B, et al., 2015, Smooth Optimal Quantum Control for Robust Solid-State Spin Magnetometry, PHYSICAL REVIEW LETTERS, Vol: 115, ISSN: 0031-9007
Tranter A, Sofia S, Seeley J, et al., 2015, The Bravyi-Kitaev transformation: Properties and applications, INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Vol: 115, Pages: 1431-1441, ISSN: 0020-7608
Cui J, Mintert F, 2015, Robust control of long-distance entanglement in disordered spin chains, New Journal of Physics, Vol: 17, ISSN: 1367-2630
We derive temporally shaped control pulses for the creation of long-distance entanglement in disordered spin chains. Our approach is based on a time-dependent target functional and a time-local control strategy that permits us to ensure that the description of the chain in terms of matrix product states is always valid. With this approach, we demonstrate that long-distance entanglement can be created even for substantially disordered interaction landscapes.
Dive B, Mintert F, Burgarth D, 2015, Quantum simulations of dissipative dynamics: Time dependence instead of size, PHYSICAL REVIEW A, Vol: 92, ISSN: 2469-9926
Verdeny A, Mintert F, 2015, Structure-dynamics relation in shaken optical lattices, PHYSICAL REVIEW A, Vol: 92, ISSN: 2469-9926
Levi F, Mostarda S, Rao F, et al., 2015, Quantum mechanics of excitation transport in photosynthetic complexes: a key issues review, REPORTS ON PROGRESS IN PHYSICS, Vol: 78, ISSN: 0034-4885
Haddadfarshi F, Cui J, Mintert F, 2015, Completely Positive Approximate Solutions of Driven Open Quantum Systems, PHYSICAL REVIEW LETTERS, Vol: 114, ISSN: 0031-9007
Ra Y-S, Tichy MC, Lim H-T, et al., 2014, Comment on 'Non-monotonic projection probabilities as a function of distinguishability', NEW JOURNAL OF PHYSICS, Vol: 16, ISSN: 1367-2630
Valido AA, Levi F, Mintert F, 2014, Hierarchies of multipartite entanglement for continuous-variable states, PHYSICAL REVIEW A, Vol: 90, ISSN: 1050-2947
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