Dynamical signatures of molecular symmetries in nonequilibrium quantum transport

Thingna, Juzar; Manzano, Daniel; Cao, Jianshu

doi:10.1038/srep28027

Cited by 57 publications

(81 citation statements)

References 62 publications

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“…From quantum cavities [1][2][3] and superconducting qubits [4][5][6][7][8][9] , through quantum dots [10][11][12][13][14][15], molecular junctions [16][17][18][19][20][21][22][23][24][25][26][27] and cold atoms [28][29][30][31] , to excitons traveling in photosynthetic complexes [32][33][34][35], open quantum systems show dynamics which can be far richer and more surprising than their coherent (environment-free) counterparts.…”

Section: A Introductionmentioning

confidence: 99%

Quantum transport under ac drive from the leads: A Redfield quantum master equation approach

Purkayastha

2017

Phys. Rev. B

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Evaluating the time-dependent dynamics of driven open quantum systems is relevant for a theoretical description of many systems, including molecular junctions, quantum dots, cavity-QED experiments, cold atoms experiments and more. Here, we formulate a rigorous microscopic theory of an out-of-equilibrium open quantum system of non-interacting particles on a lattice weakly coupled bilinearly to multiple baths and driven by periodically varying thermodynamic parameters like temperature and chemical potential of the bath. The particles can be either bosonic or fermionic and the lattice can be of any dimension and geometry. Based on Redfield quantum master equation under Born-Markov approximation, we derive a linear differential equation for equal time two-point correlation matrix, sometimes also called single-particle density matrix, from which various physical observables, for example, current, can be calculated. Various interesting physical effects, such as resonance, can be directly read-off from the equations. Thus, our theory is quite general gives quite transparent and easy-to-calculate results. We validate our theory by comparing with exact numerical simulations. We apply our method to a generic open quantum system, namely a double-quantum dot coupled to leads with modulating chemical potentials. Two most important experimentally relevant insights from this are : (i) time-dependent measurements of current for symmetric oscillating voltages (with zero instantaneous voltage bias) can point to the degree of asymmetry in the system-bath coupling, and (ii) under certain conditions, time-dependent currents can exceed time-averaged currents by several orders of magnitude, and can therefore be detected even when the average current is below the measurement threshold. A. IntroductionThe dynamics of a quantum system coupled to an external environment (so-called "open" quantum system) are a result of the intricate interplay between the coherent evolution of the quantum degrees of freedom, the structure of the environment and the form and strength of the system-environment coupling. From quantum cavities [1-3] and superconducting qubits [4][5][6][7][8][9] , through quantum dots [10][11][12][13][14][15], molecular junctions [16][17][18][19][20][21][22][23][24][25][26][27] and cold atoms [28][29][30][31] , to excitons traveling in photosynthetic complexes [32][33][34][35], open quantum systems show dynamics which can be far richer and more surprising than their coherent (environment-free) counterparts.Recent ideas of designing a quantum state by engineering a specific environment [36][37][38][39][40][41][42] or by a periodic modulation of the open system's Hamiltonian [16,43,44] open a path to new forms of control over quantum systems. Combining these two concepts of time-periodic modulations and environment (bath) engineering, here we study the dynamics of open quantum systems where the environment thermodynamic parameters are periodically modulated. Even though there exists formally exact methods of treating such set-ups...

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Section: A Introductionmentioning

confidence: 99%

Quantum transport under ac drive from the leads: A Redfield quantum master equation approach

Purkayastha

2017

Phys. Rev. B

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“…Therefore, we must impose that ( )  D A, 9 8 and therefore  P 0, to ensure that the system remain confined to Fock space for all all times. This implies that systems of non-interacting bosons which absorb particles from an external reservoir require a sufficient (as quantified by (98)) amount of dissipation to ensure the existence of a well-defined NESS 11 .…”

Section: Bosonic Systemsmentioning

confidence: 99%

“…As the sizes of technological devices driven by currents reach mesoscopic scales, non-trivial quantum effects must be taken into account [1][2][3][4]. Yet, our theoretical understanding of currents in quantum systems is far from complete, e.g., many results are available for perfect lattices [5], but more realistic set-ups, with disorder and decoherence, still pose a panoply of open questions [6][7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

On optimal currents of indistinguishable particles

2017

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We establish a mathematically rigorous, general and quantitative framework to describe currents of non-(or weakly) interacting, indistinguishable particles driven far from equilibrium. We derive tight upper and lower bounds for the achievable fermionic and bosonic steady state current, respectively, which can serve as benchmarks for special cases of interacting many-particle dynamics. For fermionic currents, we identify a symmetry-induced enhancement mechanism in parameter regimes where the coupling between system and reservoirs is weak. This mechanism is broadly applicable provided the inter-particle interaction strength is small as compared to typical exchange interactions.

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“…Nonequilibrium quantum dynamics is a rapidly growing field of study in part due to the emergence of hundreds of quantum simulator platforms build on multiple architectures, presenting enormous flexibility to explore new problems with detailed control of lattice structure, interaction strength, and bosonic or fermionic statistics [1][2][3][4]. For example, global quantum quench dynamics have led to a deep understanding of the Kibble-Zurek mechanism relating non-equilibrium dynamics to critical exponents in quantum phase transitions [5].…”

Section: Introductionmentioning

confidence: 99%

Nonequilibrium quantum dynamics of partial symmetry breaking for ultracold bosons in an optical lattice ring trap

et al. 2019

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A vortex in a Bose-Einstein condensate on a ring undergoes quantum dynamics in response to a quantum quench in terms of partial symmetry breaking from a uniform lattice to a biperiodic one. Neither the current, a macroscopic measure, nor fidelity, a microscopic measure, exhibit critical behavior. Instead, the symmetry memory succeeds in identifying the critical symmetry breaking at which the system begins to forget its initial symmetry state. We further identify a symmetry energy difference in the low lying excited states which trends with the symmetry memory.

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Dynamical signatures of molecular symmetries in nonequilibrium quantum transport

Cited by 57 publications

References 62 publications

Quantum transport under ac drive from the leads: A Redfield quantum master equation approach

Quantum transport under ac drive from the leads: A Redfield quantum master equation approach

On optimal currents of indistinguishable particles

Nonequilibrium quantum dynamics of partial symmetry breaking for ultracold bosons in an optical lattice ring trap

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