Collective Rabi Oscillations and Solitons in a Time-Dependent BCS Pairing Problem

Barankov, Roman; Levitov, L. S.; Spivak, B.

doi:10.1103/physrevlett.93.160401

Cited by 300 publications

(535 citation statements)

References 38 publications

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“…In these problems the goal is to describe the dynamics of a many-body system following a sudden perturbation that drove the system out of an equilibrium. The system in question can be a BCS superconductor [1,2,3,4,5,6,7,8,9,10,11], coupled FermiBose condensates [12,13], or a single electronic spin interacting with many nuclear spins (the central spin model) [14,15,16,17,18,19,20]. A common feature of all these problems is that they can be formulated in terms of spin Hamiltonians, which belong to a class of integrable systems known as Gaudin magnets [21,22,23].…”

Section: Introductionmentioning

confidence: 99%

Integrable dynamics of coupled Fermi-Bose condensates

2005

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We study the mean-field dynamics of a fermionic condensate interacting with a single bosonic mode (a generalized Dicke model). This problem is integrable and can be mapped onto a corresponding BCS problem. We derive the general solution and a full set of integrals of motion for the time evolution of coupled Fermi-Bose condensates. The present paper complements our earlier study of the dynamics of the BCS model (cond-mat/0407501 and cond-mat/0505493). Here we provide a self-contained introduction to the variable separation method, which enables a complete analytical description of the evolution of the generalized Dicke, BCS, and other similar models.

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Section: Introductionmentioning

confidence: 99%

Integrable dynamics of coupled Fermi-Bose condensates

2005

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“…These can be readily probed in time-of-flight [27]. The dynamics of the roton modes in this bosonic dipolar gas is analogous to that of Cooper pairs in an attractive Fermi gas, driven out of equilibrium following an interaction quench [55]. In that case, the coherent oscillation of Cooper pairs leads to oscillations in the superconducting pairing gap.…”

Section: Resultsmentioning

confidence: 99%

“…As roton excitations all oscillate at nearly the same frequency ∆, this leads to a cooperative enhancement of the signal in correlation functions. In this respect, our bosonic system displays an interesting parallel with a Fermi gas with attractive interactions, where the quench to attractive interactions leads to an enhancement of the superconducting gap [55,[70][71][72][73]. It will be extremely interesting to study whether the non-equilibrium enhancement of rotons could be a route to realizing (albeit metastable [74,75]), quantum crystalline phases of matter.…”

Section: Discussionmentioning

confidence: 99%

“…SN would like to thank V. Galitski for pointing him to Ref. [55]. SN is supported by JQI-NSF-PFC, AFOSR-MURI, and ARO-MURI.…”

Section: Acknowledgementsmentioning

confidence: 99%

“…We note that Eq. 2 is the bosonic analog of the timedependent Bogoliubov deGennes equations, which describe the dynamics of Cooper pairs following an interaction quench in a Fermi gas [55].…”

Section: A Time-dependent Bogoliubov Ansatzmentioning

confidence: 99%

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Dynamics of correlations in a quasi-two-dimensional dipolar Bose gas following a quantum quench

Natu

Campanello²,

Sarma³

2014

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We study the evolution of correlations in a quasi-2D dipolar gas driven out-of-equilibrium by a sudden ramp of the interactions. On short timescales, roton-like excitations coherently oscillate in and out of the condensate, giving rise to pronounced features in the time-evolution of the momentum distribution, excited fraction and the density-density correlation function. The evolution of these correlation functions following a quench can thus be used to probe the spectrum of the dipolar gas. We also find that density fluctuations induced by the presence of rotons following the quench, dramatically slows down the rate of spreading of correlations in the system: near the roton instability, correlations take infinitely long to build up and show deviations from light-cone like behavior.

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Recent Development of Ultrafast Optical Characterizations for Quantum Materials

2022

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or far-infrared energy region are therefore of particular importance, for the THz frequencies (1 THz≈4.1 meV) are close to the energy scales of a number of important single-particle and collective excitations of quantum material systems, for example, pairing energy gaps of superconductors, lattice vibration modes (phonons), collective spin waves (magnons), Josephson plasmon in high temperature superconductors, and binding energy of bound electron-hole pairs (excitons), [1] and they are linked to a large number of fundamental physical problems currently under intensive investigations in condensed matter physics. The information yielded from equilibrium optical measurements are usually prerequisites for understanding the nonequilibrium optical properties probed by ultrafast time-resolved spectroscopy techniques.In the last three decades, we have witnessed a rapid development in ultrafast laser and nonlinear optical techniques. The intense ultrashort optical pulses at wavelengths spanning the electromagnetic spectrum from terahertz through visible to X-ray have been generated from table-top laser sources and free-electron laser facilities. A variety of time-resolved spectroscopy techniques on the basis of pump-probe scheme have been developed. Depending on the fluence of pump pulses, photoexcitations can induce different effects and phenomena. For sufficiently weak perturbations, the photoexcitation of charge carriers does not change the free-energy landscape and the system relaxes back to the equilibrium state in a short time scale. The relaxation process is determined by the same interactions (e.g for example, electron-electron, electron-phonon) that govern the equilibrium properties. In principle, one can extract the coupling strength of electron to other degrees of freedom from the relaxation dynamics. In addition, the ultrashort laser pulse whose duration is shorter than the periodicity of targeted lattice/spin modes can trigger coherent oscillations at the corresponding frequencies of collective modes, for example, phonon, magnon, etc. with decay times that are related to the dephasing times. This enables one to detect collective-mode excitations that may not be easily accessed to or probed by other techniques.By contrast, with strong pump pulses, the photoexcitation can excite a sufficient number of electrons or drive the motion of collective mode to a large amplitude. The corresponding perturbation to the lattice/spin degrees of freedom can be large enough to modify the free-energy landscape. As a result, The advent of intense ultrashort optical pulses spanning a frequency range from terahertz to the visible has opened a new era in the experimental investigation and manipulation of quantum materials. The generation of strong optical field in an ultrashort time scale enables the steering of quantum materials nonadiabatically, inducing novel phenomenon or creating new phases which may not have an equilibrium counterpart. Ultrafast time-resolved optical techniques have provided rich information and played an im...

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Collective Rabi Oscillations and Solitons in a Time-Dependent BCS Pairing Problem

Cited by 300 publications

References 38 publications

Integrable dynamics of coupled Fermi-Bose condensates

Integrable dynamics of coupled Fermi-Bose condensates

Dynamics of correlations in a quasi-two-dimensional dipolar Bose gas following a quantum quench

Recent Development of Ultrafast Optical Characterizations for Quantum Materials

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