| 1. |
- Hagman, Henning, 1981-, et al.
(författare)
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Directed transport with real-time external steering and drifts along pre-designed paths using a Brownian motor
- 2011
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - 1063-651X .- 1095-3787. ; 83:2
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Tidskriftsartikel (refereegranskat)abstract
- We have realized real-time steering of the directed transport in a Brownian motor based on cold atoms in optical lattices and demonstrate drifts along predesigned paths. The transport is induced by spatiotemporal asymmetries in the system, where we can control the spatial part, and we show that the response to changes in asymmetry is very fast. In addition to directional steering, a real-time control of the magnitude of the average drift velocity and an on-off switching of the motor are also demonstrated. We use a noninvasive real-time detection of the transport, enabling feedback control of the system.
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| 2. |
- Kastberg, Anders, 1963-, et al.
(författare)
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A three-dimensional Brownian motor, realised with symmetric optical lattices
- 2009
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Ingår i: Physica status solidi. B, Basic research. - : Wiley. - 0370-1972 .- 1521-3951. ; 246:5, s. 999-1005
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Tidskriftsartikel (refereegranskat)abstract
- A three-dimensional Brownian motor is realised using lasercooled caesium atoms trapped in a system of two static, and individually symmetric, optical lattices; a so-called double optical lattice. Isotropic fluctuations, emanating from light scattering, are rectified, and the diffusion of the ensemble of atoms is biased, with a resulting constant velocity that is controllable both in direction and magnitude. The working principle of the Brownian motor can be seen as a pulsation between two different potentials, both symmetric but around different points. The correlation between interferometric spatial offsets, and imbalance in optical pumping rates, leads to a spatio-temporal asymmetry sufficient for generating a controlled, directed motion.
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| 3. |
- Satapathy, Nandan, et al.
(författare)
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Theoretical investigation of quantum walks by cold atoms in a double optical lattice
- 2009
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - : American Physical Society. - 1050-2947 .- 1094-1622. ; 80:1, s. 012302-
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the feasibility of carrying out quantum walks with cold atoms in a double optical lattice. Monte Carlo simulations of time-of-flight (TOF) detection and absorption imaging were carried out, focusing on a specific experimental implementation. These indicate that absorption imaging would be best suited for detection of quantum walks. With typical experimental parameters a few hundred quantum walk steps will be needed for an unambiguous detection of the quantum walk signature. We show that in special cases, few-step quantum walks can also be detected in our system if one measures the relative population of the atoms in their internal states rather than their displacement in space, that is, measurements are made in the space of the coin operator rather than in that of the displacement operator.
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| 4. |
- Zelan, Martin, 1981-, et al.
(författare)
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Experimental measurement of efficiency and transport coherence of a cold-atom Brownian motor in optical lattices
- 2011
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - : American Physical Society. - 1539-3755 .- 1550-2376. ; 83:2
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Tidskriftsartikel (refereegranskat)abstract
- The rectification of noise into directed movement or useful energy is utilized by many different systems. The peculiar nature of the energy source and conceptual differences between such Brownian motor systems makes a characterization of the performance far from straightforward. In this work, where the Brownian motor consists of atoms interacting with dissipative optical lattices, we adopt existing theory and present experimental measurements for both the efficiency and the transport coherence. We achieve up to 0.3% for the efficiency and 0.01 for the Peclet number.
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| 5. |
- Zelan, Martin, 1981-, et al.
(författare)
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Fluctuation-induced drift in a gravitationally tilted optical lattice
- 2010
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - 1063-651X .- 1095-3787. ; 82:3
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Tidskriftsartikel (refereegranskat)abstract
- Experimental and theoretical studies are made of Brownian particles trapped in a periodic potential, which is very slightly tilted due to gravity. In the presence of fluctuations, these will trigger a measurable average drift along the direction of the tilt. The magnitude of the drift varies with the ratio between the bias force and the trapping potential. This can be closely compared to a theoretical model system, based on a Fokker-Planck equation formalism. We show that the level of control and measurement precision we have in our system, which is based on cold atoms trapped in a three-dimensional dissipative optical lattice, makes the experimental setup suitable as a testbed for fundamental statistical physics. We simulate the system with a very simplified and general classical model, as well as with an elaborate semiclassical Monte Carlo simulation. In both cases, we achieve good qualitative agreement with experimental data.
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| 6. |
- Ramanathan, A., et al.
(författare)
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Superflow in a toroidal bose-einstein condensate : an atom circuit with a tunable weak link
- 2011
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 106:13
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Tidskriftsartikel (refereegranskat)abstract
- We have created a long-lived (∼40s) persistent current in a toroidal Bose-Einstein condensate held in an all-optical trap. A repulsive optical barrier across one side of the torus creates a tunable weak link in the condensate circuit, which can affect the current around the loop. Superflow stops abruptly at a barrier strength such that the local flow velocity at the barrier exceeds a critical velocity. The measured critical velocity is consistent with dissipation due to the creation of vortex-antivortex pairs. This system is the first realization of an elementary closed-loop atom circuit.
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| 7. |
- Rebolledo Salgado, Israel, 1992, et al.
(författare)
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Active Feedback Stabilization of Super-efficient Microcombs
- 2023
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Ingår i: 2023 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC). - : Institute of Electrical and Electronics Engineers (IEEE). - 2833-1052. - 9798350345995
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Konferensbidrag (refereegranskat)abstract
- We report the long-term operation of a super-efficient microcomb. We use the soliton power to maintain a fixed pump detuning. The microcomb operates over 25 hours using a thermal control in a packaged module.
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| 8. |
- Rebolledo Salgado, Israel, 1992, et al.
(författare)
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Active feedback stabilization of super-efficient microcombs in photonic molecules
- 2024
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Ingår i: Optics Letters. - : Optica Publishing Group (formerly OSA). - 0146-9592 .- 1539-4794. ; 49:9, s. 2325-2328
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Tidskriftsartikel (refereegranskat)abstract
- Dissipative Kerr soliton (DKS) frequency combs, when generated within coupled cavities, exhibit exceptional performance concerning controlled initiation and power conversion efficiency. Nevertheless, to fully exploit these enhanced capabilities, it is necessary to maintain the frequency comb in a low-noise state over an extended duration. In this study, we demonstrate the control and stabilization of super-efficient microcombs in a photonic molecule. Our findings demonstrate that there is a direct relation between effective detuning and soliton power, allowing the latter to be used as a setpoint in a feedback control loop. Employing this method, we achieve the stabilization of a highly efficient microcomb indefinitely, paving the way for its practical deployment in optical communications and dual-comb spectroscopy applications.
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| 9. |
- Rebolledo-Salgado, Israel, et al.
(författare)
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Photonic molecule microcombs at 50 GHz repetition rate
- 2022
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Ingår i: Optics InfoBase Conference Papers. - : Optica Publishing Group (formerly OSA). - 2162-2701. - 9781557528209
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Konferensbidrag (refereegranskat)abstract
- We present a microcomb in a photonic molecule with 50 GHz repetition rate. The comb attains > 50% power conversion efficiency and displays a quiet point of operation in repetition rate with decreased phase noise. © 2022 The Author(s)
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| 10. |
- Rebolledo-Salgado, Israel, et al.
(författare)
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Platicon dynamics in photonic molecules
- 2023
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Ingår i: Communications Physics. - : Nature Research. - 2399-3650. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Coherent dissipative structures known as platicons can be reliably generated in photonic molecules, resulting in deterministic and reproducible microcombs derived from a continuous-wave pump. However, the supermode spectrum of standard photonic molecules displays numerous avoided mode crossings, distorting the spectral envelope of platicon microcombs. Here, we obtain a platicon microcomb using a photonic molecule configuration based on two coupled microcavities, whose size differs by an order of magnitude. This results in an engineered microcomb spectrum that closely resembles the one generated in an ideal single microresonator with just one frequency mode shift. We observe the coupling between the repetition rate of the platicon microcomb with the frequency of the pump laser, an effect originating from the dispersive-wave recoil induced by mode crossings. Using two identical platicon microcombs, we make use of such coupling to realize dual-comb interferometry. These results contribute to understanding dissipative structures in normal-dispersion microresonators and offer an alternative to applications such as spectroscopy and metrology.
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