84 results on '"Marek, M."'
Search Results
2. Coherent Many-Body Oscillations Induced by a Superposition of Broken Symmetry States in the Wake of a Quantum Phase Transition
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Jacek Dziarmaga, Marek M. Rams, and Wojciech H. Zurek
- Subjects
Quantum Physics ,Statistical Mechanics (cond-mat.stat-mech) ,Quantum Gases (cond-mat.quant-gas) ,FOS: Physical sciences ,General Physics and Astronomy ,Quantum Physics (quant-ph) ,Condensed Matter - Quantum Gases ,Condensed Matter - Statistical Mechanics - Abstract
It is now widely accepted that quenches through the critical region of quantum phase transitions result in post-transition states populated with topological defects -- analogs of the classical topological defects. However, consequences of the very non-classical fact that the state after a quench is a {\it superposition} of distinct, broken-symmetry vacua with different numbers and locations of defects have remained largely unexplored. We identify coherent quantum oscillations induced by such superpositions in observables complementary to the one involved in symmetry breaking. These oscillations satisfy Kibble-Zurek dynamical scaling laws with the quench rate, with an instantaneous oscillation frequency set primarily by the gap of the system. In addition to the obvious fundamental significance of a superposition of different broken symmetry states, quantum coherent oscillations can be used to verify unitarity and test for imperfections of the experimental implementations of quantum simulators., version to appear in Phys. Rev. Lett. with a new example of non-integrable model
- Published
- 2022
3. Breaking the Entanglement Barrier: Tensor Network Simulation of Quantum Transport
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Rams, Marek M., primary and Zwolak, Michael, additional
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- 2020
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4. Dipolar Spin Ice States with a Fast Monopole Hopping Rate in CdEr2X4 ( X=Se , S)
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Vladimir Tsurkan, Sean Giblin, Lukas Keller, L. Prodan, Alois Loidl, Jorge Lago, Christina Ruegg, S. Vrtnik, Shang Gao, Emmanuel Canévet, Jakob Blomgren, B. Fåk, Marek M. Koza, Edvard Riordan, Clemens Ritter, Jose Luzar, Tom Fennell, Marisa Medarde, Peter Fouquet, Oksana Zaharko, Christer Johansson, and Andrew Wildes
- Subjects
Physics ,education.field_of_study ,Condensed matter physics ,Population ,Magnetic monopole ,General Physics and Astronomy ,02 engineering and technology ,Neutron scattering ,021001 nanoscience & nanotechnology ,01 natural sciences ,Inelastic neutron scattering ,Neutron spin echo ,Spin ice ,Dipole ,Crystallography ,Electric field ,0103 physical sciences ,010306 general physics ,0210 nano-technology ,education - Abstract
Excitations in a spin ice behave as magnetic monopoles, and their population and mobility control the dynamics of a spin ice at low temperature. CdEr_{2}Se_{4} is reported to have the Pauling entropy characteristic of a spin ice, but its dynamics are three orders of magnitude faster than the canonical spin ice Dy_{2}Ti_{2}O_{7}. In this Letter we use diffuse neutron scattering to show that both CdEr_{2}Se_{4} and CdEr_{2}S_{4} support a dipolar spin ice state-the host phase for a Coulomb gas of emergent magnetic monopoles. These Coulomb gases have similar parameters to those in Dy_{2}Ti_{2}O_{7}, i.e., dilute and uncorrelated, and so cannot provide three orders faster dynamics through a larger monopole population alone. We investigate the monopole dynamics using ac susceptometry and neutron spin echo spectroscopy, and verify the crystal electric field Hamiltonian of the Er^{3+} ions using inelastic neutron scattering. A quantitative calculation of the monopole hopping rate using our Coulomb gas and crystal electric field parameters shows that the fast dynamics in CdEr_{2}X_{4} (X=Se, S) are primarily due to much faster monopole hopping. Our work suggests that CdEr_{2}X_{4} offer the possibility to study alternative spin ice ground states and dynamics, with equilibration possible at much lower temperatures than the rare earth pyrochlore examples.
- Published
- 2018
5. Symmetry Breaking Bias and the Dynamics of a Quantum Phase Transition
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Rams, Marek M., primary, Dziarmaga, Jacek, additional, and Zurek, Wojciech H., additional
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- 2019
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6. Quantum fidelity in the thermodynamic limit
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Marek M. Rams and Bogdan Damski
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Quantum phase transition ,Physics ,Quantum Physics ,Quantum discord ,Statistical Mechanics (cond-mat.stat-mech) ,Strongly Correlated Electrons (cond-mat.str-el) ,Quantum dynamics ,FOS: Physical sciences ,General Physics and Astronomy ,Quantum phases ,Condensed Matter - Strongly Correlated Electrons ,Open quantum system ,Quantum mechanics ,Quantum process ,Quantum operation ,Statistical physics ,Quantum information ,Quantum Physics (quant-ph) ,Condensed Matter - Statistical Mechanics - Abstract
We study quantum fidelity, the overlap between two ground states of a many-body system, focusing on the thermodynamic regime. We show how drop of fidelity near a critical point encodes universal information about a quantum phase transition. Our general scaling results are illustrated in the quantum Ising chain for which a remarkably simple expression for fidelity is found., Comment: 4 pages, 4 figures, rearranged a bit to improve presentation
- Published
- 2010
7. Multiscale Entanglement Renormalization Ansatz in Two Dimensions: Quantum Ising Model
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Lukasz Cincio, Jacek Dziarmaga, and Marek M. Rams
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Physics ,Quantum Physics ,Quantum discord ,Statistical Mechanics (cond-mat.stat-mech) ,Strongly Correlated Electrons (cond-mat.str-el) ,Condensed Matter - Mesoscale and Nanoscale Physics ,Density matrix renormalization group ,FOS: Physical sciences ,General Physics and Astronomy ,Quantum entanglement ,Computational Physics (physics.comp-ph) ,Bethe ansatz ,Condensed Matter - Other Condensed Matter ,Renormalization ,Condensed Matter - Strongly Correlated Electrons ,Quantum mechanics ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Ising model ,Quantum algorithm ,Quantum Physics (quant-ph) ,Physics - Computational Physics ,Condensed Matter - Statistical Mechanics ,Other Condensed Matter (cond-mat.other) ,Ansatz ,Mathematical physics - Abstract
We propose a symmetric version of the multi-scale entanglement renormalization Ansatz (MERA) in two spatial dimensions (2D) and use this Ansatz to find an unknown ground state of a 2D quantum system. Results in the simple 2D quantum Ising model on the $8\times8$ square lattice are found to be very accurate even with the smallest non-trivial truncation parameter., version to appear in Phys. Rev. Letters
- Published
- 2008
8. Assisted Finite-Rate Adiabatic Passage Across a Quantum Critical Point: Exact Solution for the Quantum Ising Model
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del Campo, Adolfo, primary, Rams, Marek M., additional, and Zurek, Wojciech H., additional
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- 2012
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9. Quantum Fidelity in the Thermodynamic Limit
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Rams, Marek M., primary and Damski, Bogdan, additional
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- 2011
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10. Multiscale Entanglement Renormalization Ansatz in Two Dimensions: Quantum Ising Model
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Cincio, Lukasz, primary, Dziarmaga, Jacek, additional, and Rams, Marek M., additional
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- 2008
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11. Assisted Finite-Rate Adiabatic Passage Across a Quantum Critical Point: Exact Solution for the Quantum Ising Model.
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Campo, Adolfo del, Rams, Marek M., and Zurek, Wojciech H.
- Subjects
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ADIABATIC processes , *QUANTUM theory , *CRITICAL point (Thermodynamics) , *ISING model , *SYMMETRY breaking , *QUANTUM phase transitions , *HAMILTONIAN systems - Abstract
The dynamics of a quantum phase transition is inextricably woven with the formation of excitations, as a result of critical slowing down in the neighborhood of the critical point. We design a transitionless quantum driving through a quantum critical point, allowing one to access the ground state of the broken-symmetry phase by a finite-rate quench of the control parameter. The method is illustrated in the one-dimensional quantum Ising model in a transverse field. Driving through the critical point is assisted by an auxiliary Hamiltonian, for which the interplay between the range of the interaction and the modes where excitations are suppressed is elucidated. [ABSTRACT FROM AUTHOR]
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- 2012
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12. Antiskyrmions in Ferroelectric Barium Titanate.
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Gonçalves MAP, Paściak M, and Hlinka J
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Typical magnetic skyrmion is a string of inverted magnetization within a ferromagnet, protected by a sleeve of a vortexlike spin texture, such that its cross-section carries an integer topological charge. Some magnets form antiskyrmions, the antiparticle strings which carry an opposite topological charge. Here we demonstrate that topologically equivalent but purely electric antiskyrmion can exist in a ferroelectric material as well. In particular, our computer experiments reveal that the archetype ferroelectric, barium titanate, can host antiskyrmions at zero field. The polarization pattern around their cores reminds ring windings of decorative knots rather than the typical magnetic antiskyrmion texture. We show that the antiskyrmion of barium titanate has just 2-3 nm in diameter, a hexagonal cross section, and an exotic topological charge with doubled magnitude and opposite sign when compared to the standard skyrmion string.
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- 2024
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13. Dissipation Mechanisms in Fermionic Josephson Junction.
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Wlazłowski G, Xhani K, Tylutki M, Proukakis NP, and Magierski P
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We characterize numerically the dominant dynamical regimes in a superfluid ultracold fermionic Josephson junction. Beyond the coherent Josephson plasma regime, we discuss the onset and physical mechanism of dissipation due to the superflow exceeding a characteristic speed, and provide clear evidence distinguishing its physical mechanism across the weakly and strongly interacting limits, despite qualitative dynamics of global characteristics being only weakly sensitive to the operating dissipative mechanism. Specifically, dissipation in the strongly interacting regime occurs through the phase-slippage process, caused by the emission and propagation of quantum vortices, and sound waves-similar to the Bose-Einstein condensation limit. Instead, in the weak interaction limit, the main dissipative channel arises through the pair-breaking mechanism.
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- 2023
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14. Optical Fingerprint of Flat Substrate Surface and Marker-Free Lateral Displacement Detection with Angstrom-Level Precision.
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Lin S, He Y, Feng D, Piliarik M, and Chen XW
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- Microscopy
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We report that flat substrates such as glass coverslips with surface roughness well below 0.5 nm feature notable speckle patterns when observed with high-sensitivity interference microscopy. We uncover that these speckle patterns unambiguously originate from the subnanometer surface undulations, and develop an intuitive model to illustrate how subnanometer nonresonant dielectric features could generate pronounced interference contrast in the far field. We introduce the concept of optical fingerprint for the deterministic speckle pattern associated with a particular substrate surface area and intentionally enhance the speckle amplitudes for potential applications. We demonstrate such optical fingerprints can be leveraged for reproducible position identification and marker-free lateral displacement detection with an experimental precision of 0.22 nm. The reproducible position identification allows us to detect new nanoscopic features developed during laborious processes performed outside of the microscope. The demonstrated capability for ultrasensitive displacement detection may find applications in the semiconductor industry and superresolution optical microscopy.
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- 2022
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15. Scaling Theory of Wave Confinement in Classical and Quantum Periodic Systems.
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Kozoň M, Lagendijk A, Schlottbom M, van der Vegt JJW, and Vos WL
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Functional defects in periodic media confine waves-acoustic, electromagnetic, electronic, spin, etc.-in various dimensions, depending on the structure of the defect. While defects are usually modeled by a superlattice with a typical band-structure representation of energy levels, determining the confinement associated with a given band is highly nontrivial and no analytical method is known to date. Therefore, we propose a rigorous method to classify the dimensionality of wave confinement. Starting from the confinement energy and the mode volume, we use finite-size scaling to find that ratios of these quantities raised to certain powers yield the confinement dimensionality of each band. Our classification has negligible additional computational costs compared to a band structure calculation and is valid for any type of wave, both quantum and classical, and in any dimension. In the quantum regime, we illustrate our method on electronic confinement in 2D hexagonal boron nitride (BN) with a nitrogen vacancy, in agreement with previous results. In the classical case, we study a three-dimensional photonic band gap cavity superlattice, where we identify novel acceptorlike behavior. We briefly discuss the generalization to quasiperiodic lattices.
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- 2022
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16. Candidate Tidal Disruption Event AT2019fdr Coincident with a High-Energy Neutrino.
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Reusch S, Stein R, Kowalski M, van Velzen S, Franckowiak A, Lunardini C, Murase K, Winter W, Miller-Jones JCA, Kasliwal MM, Gilfanov M, Garrappa S, Paliya VS, Ahumada T, Anand S, Barbarino C, Bellm EC, Brinnel V, Buson S, Cenko SB, Coughlin MW, De K, Dekany R, Frederick S, Gal-Yam A, Gezari S, Giroletti M, Graham MJ, Karambelkar V, Kimura SS, Kong AKH, Kool EC, Laher RR, Medvedev P, Necker J, Nordin J, Perley DA, Rigault M, Rusholme B, Schulze S, Schweyer T, Singer LP, Sollerman J, Strotjohann NL, Sunyaev R, van Santen J, Walters R, Zhang BT, and Zimmerman E
- Abstract
The origins of the high-energy cosmic neutrino flux remain largely unknown. Recently, one high-energy neutrino was associated with a tidal disruption event (TDE). Here we present AT2019fdr, an exceptionally luminous TDE candidate, coincident with another high-energy neutrino. Our observations, including a bright dust echo and soft late-time x-ray emission, further support a TDE origin of this flare. The probability of finding two such bright events by chance is just 0.034%. We evaluate several models for neutrino production and show that AT2019fdr is capable of producing the observed high-energy neutrino, reinforcing the case for TDEs as neutrino sources.
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- 2022
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17. Dynamics of Hole Singlet-Triplet Qubits with Large g-Factor Differences.
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Jirovec D, Mutter PM, Hofmann A, Crippa A, Rychetsky M, Craig DL, Kukucka J, Martins F, Ballabio A, Ares N, Chrastina D, Isella G, Burkard G, and Katsaros G
- Abstract
The spin-orbit interaction permits to control the state of a spin qubit via electric fields. For holes it is particularly strong, allowing for fast all electrical qubit manipulation, and yet an in-depth understanding of this interaction in hole systems is missing. Here we investigate, experimentally and theoretically, the effect of the cubic Rashba spin-orbit interaction on the mixing of the spin states by studying singlet-triplet oscillations in a planar Ge hole double quantum dot. Landau-Zener sweeps at different magnetic field directions allow us to disentangle the effects of the spin-orbit induced spin-flip term from those caused by strongly site-dependent and anisotropic quantum dot g tensors. Our work, therefore, provides new insights into the hole spin-orbit interaction, necessary for optimizing future qubit experiments.
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- 2022
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18. Recovering Quantum Correlations in Optical Lattices from Interaction Quenches.
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Gluza M and Eisert J
- Abstract
Quantum simulations with ultracold atoms in optical lattices open up an exciting path toward understanding strongly interacting quantum systems. Atom gas microscopes are crucial for this as they offer single-site density resolution, unparalleled in other quantum many-body systems. However, currently a direct measurement of local coherent currents is out of reach. In this Letter, we show how to achieve that by measuring densities that are altered in response to quenches to noninteracting dynamics, e.g., after tilting the optical lattice. For this, we establish a data analysis method solving the closed set of equations relating tunneling currents and atom number dynamics, allowing us to reliably recover the full covariance matrix, including off-diagonal terms representing coherent currents. The signal processing builds upon semidefinite optimization, providing bona fide covariance matrices optimally matching the observed data. We demonstrate how the obtained information about noncommuting observables allows one to quantify entanglement at finite temperature, which opens up the possibility to study quantum correlations in quantum simulations going beyond classical capabilities.
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- 2021
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19. Cornucopia of Antineutrons and Hyperons from a Super J/ψ Factory for Next-Generation Nuclear and Particle Physics High-Precision Experiments.
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Yuan CZ and Karliner M
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In order to study the interactions and structure of various types of matter, one typically needs to carry out scattering experiments utilizing many different particles as projectiles. Whereas beams of e^{±}, μ^{±}, π^{±}, K^{±}, protons, antiprotons, and various heavy ions have been produced and have enabled many scientific breakthroughs, beams of antineutrons, hyperons (Λ, Σ, and Ξ) and their antiparticles are typically not easy to obtain. Here we point out and investigate a new high-quality source of these particles: a super-J/ψ factory with the capability of accumulating trillions of J/ψ decays each year. In the relevant J/ψ decays, the desired particle is produced together with other final-state particles that can be tagged. This allows accurate determination of the flux and momentum of the projectile, enabling unprecedented precision in the study of the corresponding interactions with a broad range of targets. These novel high-statistics sources of baryons and antibaryons with precisely known kinematics open fresh opportunities for applications in particle and nuclear physics, including antinucleon-nucleon interaction, a nonvalence ss[over ¯] component of the nucleon, (anti)hyperon-nucleon interaction, OZI violation, (multistrange) hypernuclei, exotic light hadron spectroscopy, and many others, as well as calibration of Monte Carlo simulation for hadronic and medical physics.
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- 2021
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20. Physics and Metaphysics of Wigner's Friends: Even Performed Premeasurements Have No Results.
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Żukowski M and Markiewicz M
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"The unambiguous account of proper quantum phenomena must, in principle, include a description of all relevant features of experimental arrangement" (Bohr). The measurement process is composed of premeasurement (quantum correlation of the system with the pointer variable) and an irreversible decoherence via interaction with an environment. The system ends up in a probabilistic mixture of the eigenstates of the measured observable. For the premeasurement stage, any attempt to introduce an "outcome" leads, as we show, to a logical contradiction, 1=i. This nullifies claims that a modified concept of Wigner's friend, who just premeasures, can lead to valid results concerning quantum theory.
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- 2021
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21. Emulating Quantum Teleportation of a Majorana Zero Mode Qubit.
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Huang HL, Narożniak M, Liang F, Zhao Y, Castellano AD, Gong M, Wu Y, Wang S, Lin J, Xu Y, Deng H, Rong H, Dowling JP, Peng CZ, Byrnes T, Zhu X, and Pan JW
- Abstract
Topological quantum computation based on anyons is a promising approach to achieve fault-tolerant quantum computing. The Majorana zero modes in the Kitaev chain are an example of non-Abelian anyons where braiding operations can be used to perform quantum gates. Here we perform a quantum simulation of topological quantum computing, by teleporting a qubit encoded in the Majorana zero modes of a Kitaev chain. The quantum simulation is performed by mapping the Kitaev chain to its equivalent spin version and realizing the ground states in a superconducting quantum processor. The teleportation transfers the quantum state encoded in the spin-mapped version of the Majorana zero mode states between two Kitaev chains. The teleportation circuit is realized using only braiding operations and can be achieved despite being restricted to Clifford gates for the Ising anyons. The Majorana encoding is a quantum error detecting code for phase-flip errors, which is used to improve the average fidelity of the teleportation for six distinct states from 70.76±0.35% to 84.60±0.11%, well beyond the classical bound in either case.
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- 2021
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22. Cosmic String Interpretation of NANOGrav Pulsar Timing Data.
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Ellis J and Lewicki M
- Abstract
Pulsar timing data used to provide upper limits on a possible stochastic gravitational wave background (SGWB). However, the NANOGrav Collaboration has recently reported strong evidence for a stochastic common-spectrum process, which we interpret as a SGWB in the framework of cosmic strings. The possible NANOGrav signal would correspond to a string tension Gμ∈(4×10^{-11},10^{-10}) at the 68% confidence level, with a different frequency dependence from supermassive black hole mergers. The SGWB produced by cosmic strings with such values of Gμ would be beyond the reach of LIGO, but could be measured by other planned and proposed detectors such as SKA, LISA, TianQin, AION-1 km, AEDGE, Einstein Telescope, and Cosmic Explorer.
- Published
- 2021
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23. Gravitational Wave Bursts as Harbingers of Cosmic Strings Diluted by Inflation.
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Cui Y, Lewicki M, and Morrissey DE
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A standard expectation of primordial cosmological inflation is that it dilutes all relics created before its onset to unobservable levels. We present a counterexample to this expectation by demonstrating that a network of cosmic strings diluted by inflation can regrow to a level that is potentially observable today in gravitational waves (GWs). In contrast to undiluted cosmic strings, whose primary GW signals are typically in the form of a stochastic GW background, the leading signal from a diluted cosmic string network can be distinctive bursts of GWs within the sensitivity reach of current and future GW observatories.
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- 2020
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24. Scaling and Diabatic Effects in Quantum Annealing with a D-Wave Device.
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Weinberg P, Tylutki M, Rönkkö JM, Westerholm J, Åström JA, Manninen P, Törmä P, and Sandvik AW
- Abstract
We discuss quantum annealing of the two-dimensional transverse-field Ising model on a D-Wave device, encoded on L×L lattices with L≤32. Analyzing the residual energy and deviation from maximal magnetization in the final classical state, we find an optimal L dependent annealing rate v for which the two quantities are minimized. The results are well described by a phenomenological model with two powers of v and L-dependent prefactors to describe the competing effects of reduced quantum fluctuations (for which we see evidence of the Kibble-Zurek mechanism) and increasing noise impact when v is lowered. The same scaling form also describes results of numerical solutions of a transverse-field Ising model with the spins coupled to noise sources. We explain why the optimal annealing time is much longer than the coherence time of the individual qubits.
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- 2020
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25. Observation of the Crossover from Photon Ordering to Delocalization in Tunably Coupled Resonators.
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Collodo MC, Potočnik A, Gasparinetti S, Besse JC, Pechal M, Sameti M, Hartmann MJ, Wallraff A, and Eichler C
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Networks of nonlinear resonators offer intriguing perspectives as quantum simulators for nonequilibrium many-body phases of driven-dissipative systems. Here, we employ photon correlation measurements to study the radiation fields emitted from a system of two superconducting resonators in a driven-dissipative regime, coupled nonlinearly by a superconducting quantum interference device, with cross-Kerr interactions dominating over on-site Kerr interactions. We apply a parametrically modulated magnetic flux to control the linear photon hopping rate between the two resonators and its ratio with the cross-Kerr rate. When increasing the hopping rate, we observe a crossover from an ordered to a delocalized state of photons. The presented coupling scheme is intrinsically robust to frequency disorder and may therefore prove useful for realizing larger-scale resonator arrays.
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- 2019
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26. Landau-Zener-Stückelberg-Majorana Interferometry of a Single Hole.
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Bogan A, Studenikin S, Korkusinski M, Gaudreau L, Zawadzki P, Sachrajda AS, Tracy L, Reno J, and Hargett T
- Abstract
We perform Landau-Zener-Stückelberg-Majorana (LZSM) spectroscopy on a system with strong spin-orbit interaction (SOI), realized as a single hole confined in a gated double quantum dot. Analogous to electron systems, at a magnetic field B=0 and high modulation frequencies, we observe photon-assisted tunneling between dots, which smoothly evolves into the typical LZSM funnel-shaped interference pattern as the frequency is decreased. In contrast to electrons, the SOI enables an additional, efficient spin-flip interdot tunneling channel, introducing a distinct interference pattern at finite B. Magnetotransport spectra at low-frequency LZSM driving show the two channels to be equally coherent. High-frequency LZSM driving reveals complex photon-assisted tunneling pathways, both spin conserving and spin flip, which form closed loops at critical magnetic fields. In one such loop, an arbitrary hole spin state is inverted, opening the way toward its all-electrical manipulation.
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- 2018
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27. Discovery of the Doubly Charmed Ξ_{cc} Baryon Implies a Stable bbu[over ¯]d[over ¯] Tetraquark.
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Karliner M and Rosner JL
- Abstract
Recently, the LHCb Collaboration discovered the first doubly charmed baryon Ξ_{cc}^{++}=ccu at 3621.40±0.78 MeV, very close to our theoretical prediction. We use the same methods to predict a doubly bottom tetraquark T(bbu[over ¯]d[over ¯]) with J^{P}=1^{+} at 10 389±12 MeV, 215 MeV below the B^{-}B[over ¯]^{*0} threshold and 170 MeV below the threshold for decay to B^{-}B[over ¯]^{0}γ. The T(bbu[over ¯]d[over ¯]) is therefore stable under strong and electromagnetic interactions and can only decay weakly, the first exotic hadron with such a property. On the other hand, the mass of T(ccu[over ¯]d[over ¯]) with J^{P}=1^{+} is predicted to be 3882±12 MeV, 7 MeV above the D^{0}D^{*+} threshold and 148 MeV above the D^{0}D^{+}γ threshold. T(bcu[over ¯]d[over ¯]) with J^{P}=0^{+} is predicted at 7134±13 MeV, 11 MeV below the B[over ¯]^{0}D^{0} threshold. Our precision is not sufficient to determine whether bcu[over ¯]d[over ¯] is actually above or below the threshold. It could manifest itself as a narrow resonance just at threshold.
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- 2017
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28. Correlations and Entanglement of Microwave Photons Emitted in a Cascade Decay.
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Gasparinetti S, Pechal M, Besse JC, Mondal M, Eichler C, and Wallraff A
- Abstract
We use a three-level artificial atom in the ladder configuration as a source of correlated, single microwave photons of different frequency. The artificial atom, a transmon-type superconducting circuit, is driven at the two-photon transition between ground and second-excited state, and embedded into an on-chip switch that selectively routes different-frequency photons into different spatial modes. Under continuous driving, we measure power cross-correlations between the two modes and observe a crossover between strong antibunching and superbunching, typical of cascade decay, and an oscillatory pattern as the drive strength becomes comparable to the radiative decay rate. By preparing the source in a superposition state using an excitation pulse, we achieve deterministic generation of entangled photon pairs, as demonstrated by nonvanishing phase correlations and more generally by joint quantum state tomography of the two itinerant photonic modes.
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- 2017
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29. Terahertz-Range Polar Modes in Domain-Engineered BiFeO_{3}.
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Hlinka J, Paściak M, Körbel S, and Marton P
- Abstract
The dielectric permittivity and properties of electrically active lattice resonances in nanotwinned BiFeO_{3} crystals have been studied theoretically using an earlier established interatomic potential. The results suggest that an array of 71° domain walls with about 2-5 nm spacing enhances the static permittivity of BiFeO_{3} by more than an order of magnitude. This enhancement is associated with an electrically active excitation, corresponding to a collective vibration of pinned domain walls at a remarkably high frequency of about 0.3 THz.
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- 2017
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30. Speed of Gravitational Waves from Strongly Lensed Gravitational Waves and Electromagnetic Signals.
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Fan XL, Liao K, Biesiada M, Piórkowska-Kurpas A, and Zhu ZH
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We propose a new model-independent measurement strategy for the propagation speed of gravitational waves (GWs) based on strongly lensed GWs and their electromagnetic (EM) counterparts. This can be done in two ways: by comparing arrival times of GWs and their EM counterparts and by comparing the time delays between images seen in GWs and their EM counterparts. The lensed GW-EM event is perhaps the best way to identify an EM counterpart. Conceptually, this method does not rely on any specific theory of massive gravitons or modified gravity. Its differential setting (i.e., measuring the difference between time delays in GW and EM domains) makes it robust against lens modeling details (photons and GWs travel in the same lensing potential) and against internal time delays between GW and EM emission acts. It requires, however, that the theory of gravity is metric and predicts gravitational lensing similar to general relativity. We expect that such a test will become possible in the era of third-generation gravitational-wave detectors, when about 10 lensed GW events would be observed each year. The power of this method is mainly limited by the timing accuracy of the EM counterpart, which for kilonovae is around 10^{4} s. This uncertainty can be suppressed by a factor of ∼10^{10}, if strongly lensed transients of much shorter duration associated with the GW event can be identified. Candidates for such short transients include short γ-ray bursts and fast radio bursts.
- Published
- 2017
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31. New Exotic Meson and Baryon Resonances from Doubly Heavy Hadronic Molecules.
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Karliner M and Rosner JL
- Abstract
We predict several new exotic doubly heavy hadronic resonances, inferring from the observed exotic bottomoniumlike and charmoniumlike narrow states X(3872), Z_{b}(10610), Z_{b}(10650), Z_{c}(3900), and Z_{c}(4020/4025). We interpret the binding mechanism as mostly molecularlike isospin-exchange attraction between two heavy-light mesons in a relative S-wave state. We then generalize it to other systems containing two heavy hadrons which can couple through isospin exchange. The new predicted states include resonances in meson-meson, meson-baryon, baryon-baryon, and baryon-antibaryon channels. These include those giving rise to final states involving a heavy quark Q=c,b and antiquark Q[over ¯]^{'}=c[over ¯],b[over ¯], namely, DD[over ¯]^{*}, D^{*}D[over ¯]^{*}, D^{*}B^{*}, B[over ¯]B^{*}, B[over ¯]^{*}B^{*}, Σ_{c}D[over ¯]^{*}, Σ_{c}B^{*}, Σ_{b}D[over ¯]^{*}, Σ_{b}B^{*}, Σ_{c}Σ[over ¯]_{c}, Σ_{c}Λ[over ¯]_{c}, Σ_{c}Λ[over ¯]_{b}, Σ_{b}Σ[over ¯]_{b}, Σ_{b}Λ[over ¯]_{b}, and Σ_{b}Λ[over ¯]_{c}, as well as corresponding S-wave states giving rise to QQ^{'} or Q[over ¯]Q[over ¯]^{'}.
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- 2015
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32. Two copies of the Einstein-Podolsky-Rosen state of light lead to refutation of EPR ideas.
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Rosołek K, Stobińska M, Wieśniak M, and Żukowski M
- Abstract
Bell's theorem applies to the normalizable approximations of original Einstein-Podolsky-Rosen (EPR) state. The constructions of the proof require measurements difficult to perform, and dichotomic observables. By noticing the fact that the four mode squeezed vacuum state produced in type II down-conversion can be seen both as two copies of approximate EPR states, and also as a kind of polarization supersinglet, we show a straightforward way to test violations of the EPR concepts with direct use of their state. The observables involved are simply photon numbers at outputs of polarizing beam splitters. Suitable chained Bell inequalities are based on the geometric concept of distance. For a few settings they are potentially a new tool for quantum information applications, involving observables of a nondichotomic nature, and thus of higher informational capacity. In the limit of infinitely many settings we get a Greenberger-Horne-Zeilinger-type contradiction: EPR reasoning points to a correlation, while quantum prediction is an anticorrelation. Violations of the inequalities are fully resistant to multipair emissions in Bell experiments using parametric down-conversion sources.
- Published
- 2015
- Full Text
- View/download PDF
33. Observation of solitonic vortices in Bose-Einstein condensates.
- Author
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Donadello S, Serafini S, Tylutki M, Pitaevskii LP, Dalfovo F, Lamporesi G, and Ferrari G
- Abstract
We observe solitonic vortices in an atomic Bose-Einstein condensate (BEC) after free expansion. Clear signatures of the nature of such defects are the twisted planar density depletion around the vortex line, observed in absorption images, and the double dislocation in the interference pattern obtained through homodyne techniques. Both methods allow us to determine the sign of the quantized circulation. Experimental observations agree with numerical simulations. These solitonic vortices are the decay product of phase defects of the BEC order parameter spontaneously created after a rapid quench across the BEC transition in a cigar-shaped harmonic trap and are shown to have a very long lifetime.
- Published
- 2014
- Full Text
- View/download PDF
34. Experimental tests of classical and quantum dimensionality.
- Author
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Ahrens J, Badziąg P, Pawłowski M, Zukowski M, and Bourennane M
- Abstract
We report on an experimental test of classical and quantum dimension. We have used a dimension witness that can distinguish between quantum and classical systems of dimensions two, three, and four and performed the experiment for all five cases. The witness we have chosen is a base of semi-device-independent cryptographic and randomness expansion protocols. Therefore, the part of the experiment in which qubits were used is a realization of these protocols. In our work we also present an analytic method for finding the maximum quantum value of the witness along with corresponding measurements and preparations. This method is quite general and can be applied to any linear dimension witness.
- Published
- 2014
- Full Text
- View/download PDF
35. Hyperchaotic intermittent convection in a magnetized viscous fluid.
- Author
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Macek WM and Strumik M
- Abstract
We consider a low-dimensional model of convection in a horizontally magnetized layer of a viscous fluid heated from below. We analyze in detail the stability of hydrodynamic convection for a wide range of two control parameters. Namely, when changing the initially applied temperature difference or magnetic field strength, one can see transitions from regular to irregular long-term behavior of the system, switching between chaotic, periodic, and equilibrium asymptotic solutions. It is worth noting that owing to the induced magnetic field a transition to hyperchaotic dynamics is possible for some parameters of the model. We also reveal new features of the generalized Lorenz model, including both type I and III intermittency.
- Published
- 2014
- Full Text
- View/download PDF
36. Quantum chaos in SU(3) models with trapped ions.
- Author
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Graß T, Juliá-Díaz B, Kuś M, and Lewenstein M
- Abstract
A scheme to generate long-range spin-spin interactions between three-level ions in a chain is presented, providing a feasible experimental route to the rich physics of well-known SU(3) models. In particular, we demonstrate different signatures of quantum chaos which can be controlled and observed in experiments with trapped ions.
- Published
- 2013
- Full Text
- View/download PDF
37. W+n-jet predictions at the Large Hadron Collider at next-to-leading order matched with a parton shower.
- Author
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Höche S, Krauss F, Schönherr M, and Siegert F
- Abstract
For the first time, differential cross sections for the production of W bosons in conjunction with up to three jets, computed at next-to leading order in QCD and including parton shower corrections, are presented and compared to recent experimental data from the Large Hadron Collider.
- Published
- 2013
- Full Text
- View/download PDF
38. Cystine plug and other novel mechanisms of large mechanical stability in dimeric proteins.
- Author
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Sikora M and Cieplak M
- Subjects
- Agrobacterium tumefaciens chemistry, Dimerization, Humans, Models, Chemical, Models, Molecular, Bacterial Proteins chemistry, Cystine chemistry, Nerve Tissue Proteins chemistry, Transforming Growth Factor beta2 chemistry
- Abstract
We identify three dimeric proteins whose mechanostability is anisotropic and should exceed 1 nN along some directions. They come with distinct mechanical clamps: either shear-based, or involving a cystine slipknot, or due to dragging of a cystine plug through a cystine ring. The latter two mechanisms are topological in nature; the cystine plug mechanism has not yet been discussed but it turns out to provide the largest resistance to stretching. Its possible applications in elastomers are discussed.
- Published
- 2012
- Full Text
- View/download PDF
39. Collisional Penrose process near the horizon of extreme Kerr black holes.
- Author
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Bejger M, Piran T, Abramowicz M, and Håkanson F
- Abstract
Collisions of particles in black hole ergospheres may result in an arbitrarily large center-of-mass energy. This led recently to the suggestion [M. Bañados, J. Silk, and S. M. West, Phys. Rev. Lett. 103, 111102 (2009)] that black holes can act as ultimate particle accelerators. If the energy of an outgoing particle is larger than the total energy of the infalling particles, the energy excess must come from the rotational energy of the black hole and hence, a Penrose process is involved. However, while the center-of-mass energy diverges, the position of the collision makes it impossible for energetic particles to escape to infinity. Following an earlier work on collisional Penrose processes [T. Piran and J. Shaham, Phys. Rev. D 16, 1615 (1977)], we show that even under the most favorable idealized conditions the maximal energy of an escaping particle is only a modest factor above the total initial energy of the colliding particles. This implies that one should not expect collisions around a black hole to act as spectacular cosmic accelerators.
- Published
- 2012
- Full Text
- View/download PDF
40. Are scattering properties of graphs uniquely connected to their shapes?
- Author
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Hul O, Ławniczak M, Bauch S, Sawicki A, Kuś M, and Sirko L
- Abstract
The famous question of Kac "can one hear the shape of a drum?" addressing the unique connection between the shape of a planar region and the spectrum of the corresponding Laplace operator, can be legitimately extended to scattering systems. In the modified version, one asks whether the geometry of a vibrating system can be determined by scattering experiments. We present the first experimental approach to this problem in the case of microwave graphs (networks) simulating quantum graphs. Our experimental results strongly indicate a negative answer. To demonstrate this we consider scattering from a pair of isospectral microwave networks consisting of vertices connected by microwave coaxial cables and extended to scattering systems by connecting leads to infinity to form isoscattering networks. We show that the amplitudes and phases of the determinants of the scattering matrices of such networks are the same within the experimental uncertainties. Furthermore, we demonstrate that the scattering matrices of the networks are conjugated by the so-called transplantation relation.
- Published
- 2012
- Full Text
- View/download PDF
41. Spin textures in strongly coupled electron spin and magnetic or nuclear spin systems in quantum dots.
- Author
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Abolfath RM, Korkusinski M, Brabec T, and Hawrylak P
- Abstract
Controlling electron spins strongly coupled to magnetic and nuclear spins in solid state systems is an important challenge in the field of spintronics and quantum computation. We show here that electron droplets with no net spin in semiconductor quantum dots strongly coupled with magnetic ion or nuclear spin systems break down at low temperature and form a nontrivial antiferromagnetic spatially ordered spin texture of magnetopolarons. The spatially ordered combined electron-magnetic ion spin texture, associated with spontaneous symmetry breaking in the parity of electronic charge and spin densities and magnetization of magnetic ions, emerges from an ab initio density functional approach to the electronic system coupled with mean-field approximation for the magnetic or nuclear spin system. The predicted phase diagram determines the critical temperature as a function of coupling strength and identifies possible phases of the strongly coupled spin system. The prediction may arrest fluctuations in the spin system and open the way to control, manipulate, and prepare magnetic and nuclear spin ensembles in semiconductor nanostructures.
- Published
- 2012
- Full Text
- View/download PDF
42. Feasible optical weak measurements of complementary observables via a single Hamiltonian.
- Author
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Wu S and Zukowski M
- Abstract
A general formalism for joint weak measurements of a pair of complementary observables is given. The standard process of optical three-wave mixing in a nonlinear crystal (such as in parametric down-conversion) is suitable for such tasks. To obtain the weak value of a variable A one performs weak measurements twice, with different initial states of the meter field. This seems to be a drawback, but as a compensation we get for free the weak value of a complementary variable B. The scheme is tunable and versatile: one has access to a continuous set of possible weak measurements of a pair of observables. The scheme increases signal-to-noise ratio with respect to the case without postselection.
- Published
- 2012
- Full Text
- View/download PDF
43. Atomic-scale friction on stepped surfaces of ionic crystals.
- Author
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Steiner P, Gnecco E, Krok F, Budzioch J, Walczak L, Konior J, Szymonski M, and Meyer E
- Abstract
We report on high-resolution friction force microscopy on a stepped NaCl(001) surface in ultrahigh vacuum. The measurements were performed on single cleavage step edges. When blunt tips are used, friction is found to increase while scanning both up and down a step edge. With atomically sharp tips, friction still increases upwards, but it decreases and even changes sign downwards. Our observations extend previous results obtained without resolving atomic features and are associated with the competition between the Schwöbel barrier and the asymmetric potential well accompanying the step edges.
- Published
- 2011
- Full Text
- View/download PDF
44. Oscillating solitons in a three-component Bose-Einstein condensate.
- Author
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Szankowski P, Trippenbach M, Infeld E, and Rowlands G
- Abstract
We investigate the properties of three-component Bose-Einstein condensate systems with spin exchange interactions. We consider different coupling constants from those very special ones leading to exact solutions known in the literature. When two solitons collide, a spin component oscillation of the two emerging entities is observed. This behavior seems to be generic. A mathematical model is derived for the emerging solitons. It describes the new oscillatory phenomenon extremely well. Surprisingly, the model is in fact an exact solution to the initial equations. This comes as a bonus.
- Published
- 2010
- Full Text
- View/download PDF
45. Experimental test of fidelity limits in six-photon interferometry and of rotational invariance properties of the photonic six-qubit entanglement singlet state.
- Author
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Rådmark M, Zukowski M, and Bourennane M
- Abstract
Quantum multiphoton interferometry has now reached the six-photon stage. Thus far, the observed fidelities of entangled states never reached 2/3. We report a high fidelity (estimated at 88%) experiment in which six-qubit singlet correlations were observed. With such a high fidelity we are able to demonstrate the central property of these "singlet" correlations, their "rotational invariance," by performing a full set of measurements in three complementary polarization bases. The patterns are almost indistinguishable. The data reveal genuine six-photon entanglement. We also study several five-photon states, which result upon detection of one of the photons. Multiphoton singlet states survive some types of depolarization and are thus important in quantum communication schemes.
- Published
- 2009
- Full Text
- View/download PDF
46. Optical signatures of spin polarization of carriers in quantum dots.
- Author
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Korkusinski M and Hawrylak P
- Abstract
We predict theoretically the optical signatures of spin polarization of carriers in self-assembled quantum dots. The emission spectra are mapped out as a function of increasing electron spin polarization for a fixed number of electrons and holes. The spin-polarized spectra are determined using exact diagonalization techniques for up to 12 particles, corresponding to two lowest filled shells. We predict that the spin polarization leads to photon polarization, to redshifts of emission lines due to excess exchange interactions among the spin-polarized electrons, and to a complete breakup of emission lines for spin-polarized electronic shells.
- Published
- 2008
- Full Text
- View/download PDF
47. Discriminating multipartite entangled states.
- Author
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Schmid C, Kiesel N, Laskowski W, Wieczorek W, Zukowski M, and Weinfurter H
- Abstract
The variety of multipartite entangled states enables numerous applications in novel quantum information tasks. In order to compare the suitability of different states from a theoretical point of view, classifications have been introduced. Accordingly, here we derive criteria and demonstrate how to experimentally discriminate an observed state against the ones of certain other classes of multipartite entangled states. Our method, originating in Bell inequalities, adds an important tool for the characterization of multiparty entanglement.
- Published
- 2008
- Full Text
- View/download PDF
48. Experimentally friendly geometrical criteria for entanglement.
- Author
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Badziag P, Brukner C, Laskowski W, Paterek T, and Zukowski M
- Abstract
A simple geometrical criterion gives experimentally friendly sufficient conditions for entanglement. Its generalization gives a necessary and sufficient condition. It is linked with a family of entanglement identifiers, which is strictly richer than the family of entanglement witnesses.
- Published
- 2008
- Full Text
- View/download PDF
49. Tightening of knots in proteins.
- Author
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Sułkowska JI, Sułkowski P, Szymczak P, and Cieplak M
- Subjects
- Algorithms, Diffusion, Models, Molecular, Solvents, Stochastic Processes, Temperature, Protein Conformation
- Abstract
We perform theoretical studies of stretching of 20 proteins with knots within a coarse-grained model. The knot's ends are found to jump to well defined sequential locations that are associated with sharp turns, whereas in homopolymers they diffuse around and eventually slide off. The waiting times of the jumps are increasingly stochastic as the temperature is raised. Knots typically do not return to their native locations when a protein is released after stretching.
- Published
- 2008
- Full Text
- View/download PDF
50. Heat transfer at the nanoscale: evaporation of nanodroplets.
- Author
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Hołyst R and Litniewski M
- Abstract
We demonstrate using molecular dynamics simulations of the Lennard-Jones fluid that the evaporation process of nanodroplets at the nanoscale is limited by the heat transfer. The temperature is continuous at the liquid-vapor interface if the liquid/vapor density ratio is small (of the order of 10) and discontinuous otherwise. The temperature in the vapor has a scaling form T(r,t)=T[r/R(t)], where R(t) is the radius of an evaporating droplet at time t and r is the distance from its center. Mechanical equilibrium establishes very quickly, and the pressure difference obeys the Laplace law during evaporation.
- Published
- 2008
- Full Text
- View/download PDF
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