Ratchet effect in an optical lattice with biharmonic driving: A numerical analysis

Brown, Michael; Renzoni, Ferruccio

doi:10.1103/physreva.77.033405

Cited by 22 publications

(30 citation statements)

References 38 publications

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“…It was shown that not only the strength of the ac force but also its phase is of experimental relevance [20,21]. The generalization of the monochromatic ac force to a multi-frequency ac force leads to nontrivial results in ultra cold atom dynamics [22][23][24][25][26][27][28][29][30][31][32][33]. The relationship between symmetries and transport was explored for a cold atom ratchet with multifrequency driving [25].…”

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confidence: 99%

Dynamical control in a quasi-periodically modulated optical lattice

Yüce

2013

EPL

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-We investigate quantum tunneling phenomena for an optical lattice subjected to a bichromatic ac force. We show that incommensurability of the frequencies leads to super Bloch oscillation. We propose directed super Bloch oscillation for the quasi periodically driven optical lattice. We study the dynamical localization and photon assisted tunneling for a periodical and quasi-periodical ac force.Introduction. -Quantum tunneling of particles between potential wells is a fundamental concepts in physics and used to perform measurements of forces with high sensitivity and accuracy [1]. Recent experiments on cold atoms in optical lattices subject to time-periodic perturbations have revealed details of tunneling control through an external driving field. Tunneling control in optical lattices depends in general on the form of the external potential and, in particular, on its parameters. Nontrivial dynamical effects have been demonstrated even in the absence of nonlinear atom-atom interaction. In an optical lattice, the Bloch states are completely delocalized, with the atomic wave functions extending over the whole lattice. Thus, an initially localized wave-packet spreads ballistically in time. The presence of dc force breaks the translational symmetry and suppress atomic tunneling [2,3]. The physical picture changes if the external force is ac type (optical lattice are periodically shaken back and forth). The effect of an ac force is the reduced tunneling rate. At certain shaking strengths, tunneling is lost and dynamical localization occurs [4,5]. The combined presence of both dc and ac forces leads interesting results such as directed motion, super Bloch oscillation and photon-assisted tunneling. Super Bloch oscillations over hundreds of lattice sites occur when an integer multiple of the ac frequency is slightly detuned from the Bloch frequency associated with the dc component of the force [6][7][8][9][10][11][12]. In photon assisted tunneling, wavepacket delocalization occurs for an initially localized wave packet when modulation frequency is at multiple integers of the Bloch frequency [13][14][15][16][17][18][19]. It was shown that not only the strength of the ac force but also its phase is of experimental relevance [20,21]. The generalization of the monochromatic ac force to a multi-frequency ac force leads to nontrivial results in ultra cold atom dynamics [22][23][24][25][26][27][28][29][30][31][32][33]. The relationship between symmetries and transport was explored for a cold atom ratchet with multifrequency driving [25]. It was shown that the bi-harmonic ac force stabilizes the dynamics, allowing the generation of uniform directed motion over a range of momentum much larger than what is possible with a dc bias [29]. In this paper, we study quantum tunneling phenomena for an optical lattice subjected to a

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confidence: 99%

Dynamical control in a quasi-periodically modulated optical lattice

Yüce

2013

EPL

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“…Transport properties in systems driven by this type of external stimulus have been theoretically studied mainly in the overdamped regime [13][14][15], for moderate damping [16], both experimentally and theoretically for cold atoms in the optical lattices [17][18][19], and for driven Josephson junctions [20].…”

Section: Langevin Dynamicsmentioning

confidence: 99%

Inertial Brownian motors driven by biharmonic signals

Machura¹,

Kostur²,

Łuczka³

2010

Chemical Physics

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We study transport properties of an inertial Brownian particle moving in viscous symmetric periodic structures and driven by an oscillating signal of two harmonic components. We analyze the influence of symmetric, antisymmetric and asymmetric signals on directed transport and reveal the shift symmetry of the stationary averaged velocity of the Brownian particle with respect to the relative phase of two components of the signal. The shift symmetry holds true in all regimes.Comment: 7 pages, 5 figures; On the occasion of 60th birthday of Prof. Peter Hangg

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“…Our Hamiltonian may describe, for example, cold atoms in the classical regime of µK temperatures [3,20] exposed to two counterpropagating laser beams of perpendicular polarization, preventing the occurrence of interference terms in Eq. (1).…”

Section: Setupmentioning

confidence: 99%

“…This can be seen as a working principle of a motor operating on smallest scales relevant to phenomena ranging from intracellular transport problems [13] and cancer cell metastasis [14] to the transport of colloidal particles [15,16] in optical lattices or vortices in Josephson junction arrays [17]. Novel ratchet experiments using atomic ensembles in ac-driven optical lattices [18,19] allow for an admirable controllability both in the ultracold quantum regime [1] and at micro kelvin temperatures where a classical dynamics approach successfully describes experiments [3,20]. Naturally in view of their widespread applications, the controllability of directed particle currents has been a focal point of research since the early days of ratchet physics.…”

Section: Introductionmentioning

confidence: 99%

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Freezing, accelerating, and slowing directed currents in real time with superimposed driven lattices

et al. 2016

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We provide a generic scheme offering real time control of directed particle transport in superimposed driven lattices. This scheme allows to accelerate, slow and freeze the transport on demand, by switching one of the lattices subsequently on and off. The underlying physical mechanism hinges on a systematic opening and closing of channels between transporting and non-transporting phase space structures upon switching, and exploits cantori structures which generate memory effects in the population of these structures. Our results should allow for real time control of cold thermal atomic ensembles in optical lattices, but might also be useful as a design principle for targeted delivery of molecules or colloids in optical devices.

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Ratchet effect in an optical lattice with biharmonic driving: A numerical analysis

Cited by 22 publications

References 38 publications

Dynamical control in a quasi-periodically modulated optical lattice

Dynamical control in a quasi-periodically modulated optical lattice

Inertial Brownian motors driven by biharmonic signals

Freezing, accelerating, and slowing directed currents in real time with superimposed driven lattices

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