scholarly journals Cavity-mediated collective spin-exchange interactions in a strontium superradiant laser

Science ◽  
2018 ◽  
Vol 361 (6399) ◽  
pp. 259-262 ◽  
Author(s):  
Matthew A. Norcia ◽  
Robert J. Lewis-Swan ◽  
Julia R. K. Cline ◽  
Bihui Zhu ◽  
Ana M. Rey ◽  
...  
Keyword(s):  
Spin Exchange ◽  
Energy Gap ◽  
Optical Cavity ◽  
Exchange Interactions ◽  
Quantum Correlations ◽  
Future Design ◽  
Quantum Simulators ◽  
Spin Interactions ◽  
And Control ◽  
Body Energy

Laser-cooled and quantum degenerate atoms are being pursued as quantum simulators and form the basis of today’s most precise sensors. A key challenge toward these goals is to understand and control coherent interactions between the atoms. We observe long-range exchange interactions mediated by an optical cavity, which manifest as tunable spin-spin interactions on the pseudo spin-½ system composed of the millihertz linewidth clock transition in strontium. This leads to one-axis twisting dynamics, the emergence of a many-body energy gap, and gap protection of the optical coherence against certain sources of decoherence. Our observations will aid in the future design of versatile quantum simulators and the next generation of atomic clocks that use quantum correlations for enhanced metrology.

Spin exchange interactions in hexagonal manganites RMnO3 (R = Tb, Dy, Ho, Er) epitaxial thin films

2011 ◽  
Vol 99 (5) ◽  
pp. 052506 ◽  
Author(s):  
Xiang-Bai Chen ◽  
Nguyen Thi Minh Hien ◽  
D. Lee ◽  
S.-Y. Jang ◽  
T. W. Noh ◽  
...  
Keyword(s):  
Thin Films ◽  
Spin Exchange ◽  
Exchange Interactions ◽  
Epitaxial Thin Films ◽  
Hexagonal Manganites

scholarly journals Disentangling orbital and spin exchange interactions for Co2+ on a rocksalt lattice

2018 ◽  
Vol 98 (2) ◽  
Author(s):  
P. M. Sarte ◽  
R. A. Cowley ◽  
E. E. Rodriguez ◽  
E. Pachoud ◽  
D. Le ◽  
...  
Keyword(s):  
Spin Exchange ◽  
Exchange Interactions

Dissociation of enhanced efficiency of fat deposition during weight recovery from sympathetic control of thermogenesis

1995 ◽  
Vol 269 (2) ◽  
pp. R365-R369 ◽  
Author(s):  
A. G. Dulloo ◽  
J. Seydoux ◽  
L. Girardier
Keyword(s):  
Lower Energy ◽  
Fat Deposition ◽  
Energy Deficit ◽  
Energetic Efficiency ◽  
Sympathetic Control ◽  
Energy Conserving ◽  
And Control ◽  
Body Energy ◽  
Environmental Temperatures ◽  
Very High

Studies reported here examined the extent to which conditions known to suppress or markedly increase the sympathetic control of thermogenesis influence enhanced efficiency of fat deposition during weight recovery after caloric restriction. To this end, measurements of energy balance and changes in body energy compartments during refeeding of rats pair fed with weight-matched controls were conducted over a 2-wk period at 22 degrees C, at thermoneutrality (29 degrees C), or in the cold (6 degrees C). The results indicate that, despite identical (or slightly lower) energy intake relative to the respective controls, the refed animals showed greater gain in body fat (by 2- to 2.5-fold), 10-12% lower energy expenditure, and higher energetic efficiency (60-80%) than the controls at all three environmental temperatures. In contrast, protein gain was not different between the refed and control groups. Thus the energy-conserving mechanism specific to acceleration of fat deposition during weight recovery persists when sympathetically driven thermogenesis is shifted from very low to very high intensity. These findings raise the possibility that this energy-conserving mechanism during refeeding may be distinct from sympathetic-dependent mechanisms underlying adaptive reduction in thermogenesis during severe energy deficit and weight loss.

Steady-state quantum correlation measurement in hybrid optomechanical systems

2020 ◽  
pp. 2050046
Author(s):  
Tesfay Gebremariam Tesfahannes ◽  
Merkebu Dereje Getahune
Keyword(s):  
Correlation Function ◽  
Steady State ◽  
Quantum Entanglement ◽  
Quantum Correlation ◽  
Optical Cavity ◽  
Quantum Correlations ◽  
Correlation Measurement ◽  
Atomic Ensemble ◽  
Optomechanical System ◽  
Optomechanical Systems

In this paper, we investigate the steady-state of quantum correlation measurement of hybrid optomechanical systems. The first system consists of a single optomechanical system simultaneously coupled to a mechanical oscillator. While the second system is a hybrid optomechanical system consisting of an atomic ensemble placed in between the optical cavity and mirror. For both optomechanical systems, we formulate the Hamiltonian and the explicit expression of the covariance matrix leading to the dynamic of the system. Under the linearization approximation, we investigate the steady-state quantum correlations which are quantified through the correlation function of non-Hermitian operators, while the logarithmic negativity is used to quantify the amount of quantum entanglement between the subsystems. Furthermore, our proposed quantum correlation function can be used to quantify the entangled bipartite states that are correlative and transfer information. It is found that the transfer of quantum correlations between the subsystem is related to the detuning and coupling strength. Our results provide a realistic route toward remote quantum entanglement detection and a framework of future realistic fiber-optic quantum network operating applications.

EXACT SOLUTIONS IN A SPATIALLY ANISOTROPIC QUANTUM SPIN LADDER MODEL HAVING TWO- AND FOUR-SPIN EXCHANGE INTERACTIONS

2009 ◽  
Vol 23 (08) ◽  
pp. 1981-2019 ◽  
Author(s):  
J. H. BARRY ◽  
J. D. COHEN ◽  
M. W. MEISEL
Keyword(s):  
Spin Exchange ◽  
Inelastic Neutron Scattering ◽  
Exchange Interactions ◽  
Inelastic Neutron ◽  
Elementary Excitation ◽  
Quantum Spin ◽  
Quantum Model ◽  
Spin Ladder ◽  
Zero Field ◽  
Ladder Model

We consider a two-leg S=1/2 quantum spin ladder model with two-spin (intra-rung) and four-spin (inter-rung) Heisenberg exchange interactions and a uniform magnetic field. Exact mappings are derived connecting the partition function and correlations in the three-parameter quantum model to those known in a two-parameter Ising chain. The quantum phase diagram of the ladder magnet is determined. Static correlations provide pertinent correlation lengths and underlie spatial fluctuation behaviors at arbitrary temperatures, including quantum fluctuations at absolute zero. Dynamic correlations in zero field are used to obtain an exact solution for the inelastic neutron scattering function Sxx(q, ω) at all temperatures, explicitly yielding the elementary excitation spectrum.

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