ANTHONY LEGGETT: FEENBERG MEDALIST 1999 CONDENSED MATTER AS A TEST-BED FOR FUNDAMENTAL QUANTUM MECHANICS

2001 ◽  
Vol 15 (10n11) ◽  
pp. 1305-1311 ◽  
Author(s):  
C. E. CAMPBELL ◽  
J. W. CLARK ◽  
E. KROTSCHECK ◽  
L. P. PITAEVSKII
Keyword(s):  
Quantum Coherence ◽  
High Temperature Superconductivity ◽  
Einstein Condensation ◽  
Test Bed ◽  
Many Body ◽  
Atomic Systems ◽  
Liquid Theory ◽  
Macroscopic Quantum Coherence ◽  
Key Aspects ◽  
Bose Einstein

The Eugene Feenberg Medal is awarded to Anthony J. Leggett in recognition of his seminal contributions to Many-Body Physics, including the explanation of the remarkable properties of superfluid 3 He in the millikelvin regime, important results in Fermi-liquid theory applied to metals, fundamental new insights into macroscopic quantum coherence, elucidation of key aspects of high-temperature superconductivity, and pioneering studies of the implications of Bose-Einstein condensation in atomic systems.

scholarly journals TOPOLOGY INDUCED MACROSCOPIC QUANTUM COHERENCE IN JOSEPHSON JUNCTION NETWORKS

2004 ◽  
Vol 18 (04n05) ◽  
pp. 691-704 ◽  
Author(s):  
GIOVANNI GIUSIANO ◽  
FRANCESCO P. MANCINI ◽  
PASQUALE SODANO ◽  
ANDREA TROMBETTONI
Keyword(s):  
Josephson Junction ◽  
Coherent States ◽  
Quantum Coherence ◽  
Einstein Condensation ◽  
Macroscopic Quantum ◽  
Bose Einstein Condensation ◽  
Thermodynamical Properties ◽  
Quantum Properties ◽  
Macroscopic Quantum Coherence ◽  
Bose Einstein

We argue that Josephson junction networks may be engineered to allow for the emergence of new and robust quantum coherent states. We provide a rather intuitive argument showing how the change in topology may affect the quantum properties of a bosonic particle hopping on a network. As a paradigmatic example, we analyze in detail the quantum and thermodynamical properties of non-interacting bosons hopping on a comb graph. We show how to explicitly compute the inhomogeneities in the distribution of bosons along the comb's fingers, evidencing the effects of the topology induced spatial Bose–Einstein condensation characteristic of the system. We propose an experiment enabling to detect the spatial Bose–Einstein condensation for Josephson networks built on comb graphs.

scholarly journals What is strange about high-temperature superconductivity in cuprates?

2017 ◽  
Vol 31 (25) ◽  
pp. 1745005
Author(s):  
I. Božović ◽  
X. He ◽  
J. Wu ◽  
A. T. Bollinger
Keyword(s):  
Phase Diagram ◽  
Cuprate Superconductors ◽  
High Temperature Superconductivity ◽  
Einstein Condensation ◽  
Strongly Correlated ◽  
Bose Einstein Condensation ◽  
Ultimate Question ◽  
Underdoped Cuprates ◽  
Bose Einstein ◽  
Superconducting Parameters

Cuprate superconductors exhibit many features, but the ultimate question is why the critical temperature ([Formula: see text]) is so high. The fundamental dichotomy is between the weak-pairing, Bardeen–Cooper–Schrieffer (BCS) scenario, and Bose–Einstein condensation (BEC) of strongly-bound pairs. While for underdoped cuprates it is hotly debated which of these pictures is appropriate, it is commonly believed that on the overdoped side strongly-correlated fermion physics evolves smoothly into the conventional BCS behavior. Here, we test this dogma by studying the dependence of key superconducting parameters on doping, temperature, and external fields, in thousands of cuprate samples. The findings do not conform to BCS predictions anywhere in the phase diagram.

scholarly journals Distillation of maximally correlated bosonic matter from many-body quantum coherence

Quantum ◽  
2020 ◽  
Vol 4 ◽  
pp. 330
Author(s):  
Tyler J. Volkoff
Keyword(s):  
Quantum Coherence ◽  
Particle Number ◽  
Fock Space ◽  
Continuous Variable ◽  
Squeezed States ◽  
Discrete Variable ◽  
Many Body ◽  
Information Theoretic ◽  
Bose Einstein ◽  
Single Particle Basis

We construct quantum coherence resource theories in symmetrized Fock space (QCRTF), thereby providing an information-theoretic framework that connects analyses of quantum coherence in discrete-variable (DV) and continuous variable (CV) bosonic systems. Unlike traditional quantum coherence resource theories, QCRTF can be made independent of the single-particle basis and allow to quantify coherence within and between particle number sectors. For example, QCRTF can be formulated in such a way that neither Bose-Einstein condensates nor Heisenberg-Weyl coherent states are considered as quantum many-body coherence resources, whereas spin-squeezed and quadrature squeezed states are. The QCRTF framework is utilized to calculate the optimal asymptotic distillation rate of maximally correlated bosonic states both for particle number conserving resource states and resource states of indefinite particle number. In particular, we show how to generate a uniform superposition of maximally correlated bosonic states from a state of maximal bosonic coherence with asymptotically unit efficiency using only free operations in the QCRTF.

scholarly journals Strongly correlated superfluid order parameters from dc Josephson supercurrents

Science ◽  
2020 ◽  
Vol 369 (6499) ◽  
pp. 84-88 ◽  
Author(s):  
W. J. Kwon ◽  
G. Del Pace ◽  
R. Panza ◽  
M. Inguscio ◽  
W. Zwerger ◽  
...  
Keyword(s):  
Order Parameters ◽  
Current Phase ◽  
Einstein Condensation ◽  
Strongly Correlated ◽  
Strong Correlations ◽  
Atomic Systems ◽  
Zero Resistance ◽  
Resistance State ◽  
Sinusoidal Current ◽  
Bose Einstein

The direct-current (dc) Josephson effect provides a phase-sensitive tool for investigating superfluid order parameters. We report on the observation of dc Josephson supercurrents in strongly interacting fermionic superfluids across a tunneling barrier in the absence of any applied potential difference. For sufficiently strong barriers, we observed a sinusoidal current-phase relation, in agreement with Josephson’s seminal prediction. We mapped out the zero-resistance state and its breakdown as a function of junction parameters, extracting the Josephson critical current behavior. By comparing our results with an analytic model, we determined the pair condensate fraction throughout the Bardeen-Cooper-Schrieffer–Bose-Einstein condensation crossover. Our work suggests that coherent Josephson transport may be used to pin down superfluid order parameters in diverse atomic systems, even in the presence of strong correlations.

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