Studies of Condensed Matter at Low Temperatures by Ultrasonic and other Mechanical Spectroscopies

2012 ◽  
Vol 184 ◽  
pp. 17-23
Author(s):  
Charles Elbaum
Keyword(s):  
Low Temperatures ◽  
Cold Atoms ◽  
High Temperature Superconductivity ◽  
Condensed Matter ◽  
Solid Helium ◽  
First Century ◽  
Einstein Condensation ◽  
Mechanical Spectroscopy ◽  
Bose Einstein ◽  
New Phenomena

In the second half of the twentieth century and in the first decade of the twenty first century, many new phenomena came to light in the fields of condensed matter and of materials properties’ at low temperatures. A few examples of these phenomena are: the plasticity and the behavior of dislocations in solid helium-4 (a quantum solid), “high” temperature superconductivity, occurrence of superfluid flow in solid helium (“supersolid”), and, Bose-Einstein condensation of cold atoms. In this presentation descriptions and some discussions are given on the role played in these studies by ultrasonic and other forms of mechanical spectroscopy.

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 Bose-Einstein Condensation of Confined Atomic Gases at Ultra Low Temperatures

2017 ◽  
Vol 9 (5) ◽  
pp. 96
Author(s):  
M. Serhan
Keyword(s):  
Low Temperatures ◽  
Chemical Potential ◽  
Scattering Length ◽  
Einstein Condensation ◽  
Pitaevskii Equation ◽  
Atomic Gases ◽  
Bose Einstein Condensation ◽  
Gaussian Type ◽  
Negative Scattering Length ◽  
Bose Einstein

In this work I solve the Gross-Pitaevskii equation describing an atomic gas confined in an isotropic harmonic trap by introducing a variational wavefunction of Gaussian type. The chemical potential of the system is calculated and the solutions are discussed in the weakly and strongly interacting regimes. For the attractive system with negative scattering length the maximum number of atoms that can be put in the condensate without collapse begins is calculated.

BOSE–EINSTEIN CONDENSATION IN BULK AND CONFINED SOLID HELIUM

2006 ◽  
Vol 20 (30n31) ◽  
pp. 5081-5092 ◽  
Author(s):  
L. REATTO ◽  
M. ROSSI ◽  
D. E. GALLI
Keyword(s):  
Wave Function ◽  
Ground State ◽  
Solid Helium ◽  
System Size ◽  
Einstein Condensation ◽  
Cylindrical Pore ◽  
Simulated System ◽  
The One ◽  
Bose Einstein ◽  
Energy Computation

We address the question if the ground state of solid 4 He has the number of lattice sites equal to the number of atoms (commensurate state) or if it is different (incommensurate state). We point out that energy computation from simulation as performed by now cannot be used to decide this question and that the presently best variational wave function, a shadow wave function, gives an incommensurate state. We have extended the calculation of the one–body density matrix ρ1 to the exact Shadow Path Integral Ground State method. Calculation of ρ1 at ρ = 0.031 Å-3 shows that Vacancy–Interstitial pair processes are present also in the exact computation but the simulated system size is too small to infer the presence of off–diagonal long range order. Variational simulations of 4 He confined in a narrow cylindrical pore are also discussed.

Possible Bose-Einstein Condensation of Polygonal Clusters in 2D-Materials

2019 ◽  
Vol 297 ◽  
pp. 204-208
Author(s):  
Abid Boudiar
Keyword(s):  
Free Energy ◽  
Critical Temperature ◽  
Ground State ◽  
Low Temperatures ◽  
2D Materials ◽  
Equilibrium Structure ◽  
Einstein Condensation ◽  
Bose Einstein Condensation ◽  
Exchange Approximation ◽  
Bose Einstein

This study investigates the possibility of Bose-Einstein condensation (BEC) in 2D-nanoclusters. A ground state equilibrium structure involves the single phonon exchange approximation. At critical temperature, the specific heat, entropy, and free energy of the system can be determined. The results support the existence of BEC in nanoclusters, and they lead to predictions of the behaviour of 2Dmaterials at low temperatures.

Thermodynamic Properties of Bosons in Symmetric Double-well Potentials

1999 ◽  
Vol 54 (3-4) ◽  
pp. 204-212
Author(s):  
J. Choy ◽  
K. L. Liu ◽  
C. F. Lo ◽  
F. So
Keyword(s):  
Thermodynamic Properties ◽  
Excited States ◽  
Low Temperatures ◽  
Three Dimensional ◽  
Energy Difference ◽  
Einstein Condensation ◽  
Thermal Variation ◽  
Bose Einstein Condensation ◽  
Bose Einstein ◽  
Double Well Potential

We study the thermodynamic properties and the Bose-Einstein condensation (BEC) for a finite num-ber N of identical non-interacting bosons in the field of a deep symmetric double-well potential (SDWP). The temperature dependence of the heat capacity C(T) at low temperatures is analyzed, and we derive several generic results which are valid when the energy difference between the first two excited states is sufficiently large. We also investigate numerically the properties of non-interacting bosons in three-dimensional superpositions of deep quartic SDWP's. At low temperatures, we find that C(T) displays microstructures which are sensitive to the value of N and the thermal variation of the condensate frac-tion shows a characteristic plateau. The origin of these features is discussed, and some general conclu-sions are drawn.

scholarly journals Fluctuations and temperature effects in bose-einstein condensation

2018 ◽  
Vol 61 ◽  
pp. 55-67
Author(s):  
Anne de Bouard ◽  
Arnaud Debussche ◽  
Reika Fukuizumi ◽  
Romain Poncet
Keyword(s):  
Temperature Effects ◽  
Cold Atoms ◽  
Numerical Results ◽  
Theoretical Physics ◽  
Einstein Condensation ◽  
Bose Einstein Condensation ◽  
Physics Community ◽  
Bose Einstein

The modeling of cold atoms systems has known an increasing interest in the theoretical physics community, after the first experimental realizations of Bose Einstein condensates, some twenty years ago. We here review some analytical and numerical results concerning the influence of fluctua-tions, either arising from fluctuations of the confining parameters, or due to temperature effects, in the models describing the dynamics of such condensates.

scholarly journals Anomalous magnetoresistance due to longitudinal spin fluctuations in a Jeff = 1/2 Mott semiconductor

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Lin Hao ◽  
Zhentao Wang ◽  
Junyi Yang ◽  
D. Meyers ◽  
Joshua Sanchez ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperature Superconductivity ◽  
Spin Fluctuations ◽  
Square Lattice ◽  
External Control ◽  
Antiferromagnetic Order ◽  
Einstein Condensation ◽  
Emergent Phenomena ◽  
Longitudinal Spin ◽  
Bose Einstein

AbstractAs a hallmark of electronic correlation, spin-charge interplay underlies many emergent phenomena in doped Mott insulators, such as high-temperature superconductivity, whereas the half-filled parent state is usually electronically frozen with an antiferromagnetic order that resists external control. We report on the observation of a positive magnetoresistance that probes the staggered susceptibility of a pseudospin-half square-lattice Mott insulator built as an artificial SrIrO3/SrTiO3 superlattice. Its size is particularly large in the high-temperature insulating paramagnetic phase near the Néel transition. This magnetoresistance originates from a collective charge response to the large longitudinal spin fluctuations under a linear coupling between the external magnetic field and the staggered magnetization enabled by strong spin-orbit interaction. Our results demonstrate a magnetic control of the binding energy of the fluctuating particle-hole pairs in the Slater-Mott crossover regime analogous to the Bardeen-Cooper-Schrieffer-to-Bose-Einstein condensation crossover of ultracold-superfluids.

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.

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