| 1. |
- Atalaya, Juan, 1981, et al.
(författare)
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Spintronics-based mesoscopic heat engine
- 2012
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Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 85:24, s. Article Number: 245309 -
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Tidskriftsartikel (refereegranskat)abstract
- We consider a nanowire suspended between two spin-polarized leads and subjected to a nonuniform magnetic field. We show that a temperature drop between the leads can significantly affect the nanowire dynamics. In particular, it is demonstrated that, under certain conditions, the stationary distribution of the mechanical subsystem has a Boltzmann form with an effective temperature, which is lower than the temperature of the "cold" lead; this seems rather counterintuitive. We also find that a change in the direction of the temperature gradient can result in the generation of mechanical vibrations rather than the heating of the mechanical subsystem.
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| 2. |
- Gorelik, Leonid, 1952, et al.
(författare)
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Suppression of thermal fluctuations of nanomechanical resonator (ground state cooling) by thermally activated electronic flow
- 2011
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Ingår i: 21st International Conference on Noise and Fluctuations, ICNF 2011; Toronto, ON; 12 June 2011 through 16 June 2011. - 9781457701924 ; , s. 223-226
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Konferensbidrag (refereegranskat)abstract
- We consider a doubly clamped suspended metallic carbon nanotube in which extra charge is injected from the tipof a scanning tunneling microscopy (STM). Our analysis shows that the quantum superposition between the different inelastic electronic tunneling paths can be controlled by the bias voltage. In particular, we find that below Coulomb blockade threshold the vibron emission induced by thermally activated electron transportation can be significantly reduced in comparison to the vibron absorption. As a consequence a net suppression of the thermal fluctuations ("cooling") of the vibrational degrees of freedom can be achieved. © 2011 IEEE.
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| 3. |
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| 4. |
- Kiselev, M. N., et al.
(författare)
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Kondo Force in Shuttling Devices: Dynamical Probe for a Kondo Cloud
- 2013
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 110:6
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Tidskriftsartikel (refereegranskat)abstract
- Abstract: We consider the electromechanical properties of a single-electronic device consisting of a movable quantum dot attached to a vibrating cantilever, forming a tunnel contact with a nonmovable source electrode. We show that the resonance Kondo tunneling of electrons amplifies exponentially the strength of nanoelectromechanical (NEM) coupling in such a device and make the latter insensitive to mesoscopic fluctuations of electronic levels in a nanodot. It is also shown that the study of a Kondo-NEM phenomenon provides additional (as compared with standard conductance measurements in a nonmechanical device) information on retardation effects in the formation of a many-particle cloud accompanying the Kondo tunneling. A possibility for superhigh tunability of mechanical dissipation as well as supersensitive detection of mechanical displacement is demonstrated.
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| 5. |
- Kulinich, Sergeij I., et al.
(författare)
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Nanomechanics of a magnetic shuttle device
- 2014
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Ingår i: Low temperature physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 40:10, s. 1161-1169
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Tidskriftsartikel (refereegranskat)abstract
- We show that self sustained mechanical vibrations in a model magnetic shuttle device can be driven by both the charge and the spin accumulated on the movable central island of the device. Different scenarios for how spin- and charge-induced shuttle instabilities may develop are discussed and shown to depend on whether there is a Coulomb blockade of tunneling or not. The crucial role of electronic spin flips in a magnetically driven shuttle is established and shown to cause giant magnetoresistance and dynamic magnetostriction effects.
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| 6. |
- Kulinich, Sergeij I., et al.
(författare)
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Single-Electron Shuttle Based on Electron Spin
- 2014
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 112:11
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Tidskriftsartikel (refereegranskat)abstract
- A nanoelectromechanical device based on magnetic exchange forces and electron spin flips induced by a weak external magnetic field is suggested. It is shown that this device can operate as a new type of single-electron "shuttle" in the Coulomb blockade regime of electron transport.
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| 7. |
- Kulinich, Sergeij I., et al.
(författare)
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Umklapp-assisted electron transport oscillations in metal superlattices
- 2012
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Ingår i: Physical Review B. - 1098-0121. ; 85:18, s. artikel nr 184202-
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Tidskriftsartikel (refereegranskat)abstract
- We consider a superlattice of parallel metal tunnel junctions with a spatially nonhomogeneous probability for electrons to tunnel. In such structures tunneling can be accompanied by electron scattering that conserves energy but not momentum. In the special case of a tunneling probability that varies periodically with period a in the longitudinal direction, i.e., perpendicular to the junctions, electron tunneling is accompanied by umklapp scattering, where the longitudinal momentum changes by a multiple of h/a. We predict that as a result a sequence of metal-insulator transitions can be induced by an external electric or magnetic field as the field strength is increased.
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| 8. |
- Nordenfelt, Anders, et al.
(författare)
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Magnetomotive Instability and Generation of Mechanical Vibrations in Suspended Semiconducting Carbon Nanotubes
- 2010
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 12:12
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the electromechanics of a freely suspended semiconducting carbon nanotube subjected to a magnetic field H in the current-biased regime and show that self-excitation of mechanical nanotube vibrations can occur if H exceeds a critical value Hc of the order of 10–100 mT. The effect can be detected by measuring the magnetic field dependence of the time-averaged voltage drop across the nanotube, which has a singularity at H=Hc. We discuss the applications of the device as an active, tuneable radiofrequency oscillator.
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| 9. |
- Peña-Aza, Milton Eduardo, 1981, et al.
(författare)
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Parametric excitation of dc current in a single-dot shuttle system via spontaneous symmetry breaking
- 2013
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Ingår i: Physical Review B. - 1098-0121. ; 88:3, s. artikel nr 035412-
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Tidskriftsartikel (refereegranskat)abstract
- We investigate theoretically the dynamics of a spatially symmetric shuttle system subjected to an ac gate voltage. We demonstrate that in such a system parametric excitation gives rise to mechanical vibrations when the frequency of the ac signal is close to the eigenfrequency of the mechanical subsystem. These mechanical oscillations result in a dc shuttle current in a certain direction due to spontaneous symmetry breaking. The direction of the current is determined by the phase shift between the ac gate voltage and the parametrically excited mechanical oscillations. The dependence of the shuttle current on the dc gate voltage is also analyzed.
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| 10. |
- Radic, D., et al.
(författare)
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Quantum Theory of Magnetoelectromotive Instability in Nanoelectromechanical Systems with Positive Differential Conductance
- 2013
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 111:18, s. 5-
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Tidskriftsartikel (refereegranskat)abstract
- We consider dc-electronic transport through a nanowire suspended between two normal-metal leads in the presence of an external magnetic field. We show the very mechanism through which such a system, whose stationary current-voltage characteristic is essentially characterized by positive differential conductance, becomes unstable with respect to an onset of self-excited oscillations in electrical transport and mechanical vibrations. The self-excitation mechanism is based on the correlation between the occupancy of the quantized spin-split electronic energy levels inside the nanowire and the velocity of the nanowire with the crucial influence of strong enough retardation effects in magnetomotive coupling coming from mechanical vibrations.
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| 11. |
- Radic, Danko, 1970, et al.
(författare)
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Self-excited oscillations of charge-spin accumulation due to single-electron tunneling
- 2010
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Ingår i: Physical Review B. - 1098-0121. ; 82:12, s. 125311 (7 pages)-
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Tidskriftsartikel (refereegranskat)abstract
- We theoretically study electronic transport through a layer of quantum dots connecting two metallic leads. By the inclusion of an inductor in series with the junction, we show that steady electronic transport in such a system may be unstable with respect to temporal oscillations caused by an interplay between the Coulomb blockade of tunneling and spin accumulation in the dots. When this instability occurs, a new stable regime is reached, where the average spin and charge in the dots oscillate periodically in time. The frequency of these oscillations is typically on the order of 1 GHz for realistic values of the junction parameters.
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| 12. |
- Radic, Danko, 1970, et al.
(författare)
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Spin-controlled nanomechanics induced by single-electron tunneling
- 2011
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 107:23
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Tidskriftsartikel (refereegranskat)abstract
- We consider dc-electronic transport through a nanowire suspended between normal- and spin-polarized metal leads in the presence of an external magnetic field. We show that magnetomotive coupling between the electrical current through the nanowire and vibrations of the wire may result in self-excitation of mechanical vibrations. The self-excitation mechanism is based on correlations between the occupancy of the quantized electronic energy levels inside the nanowire and the velocity of the nanowire. We derive conditions for the occurrence of the instability and find stable regimes of mechanical oscillations.
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| 13. |
- Santandrea, Fabio, 1981, et al.
(författare)
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Cooling of Nanomechanical Resonators by Thermally Activated Single-Electron Transport
- 2011
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 106:18
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Tidskriftsartikel (refereegranskat)abstract
- We show that the vibrations of a nanomechanical resonator can be cooled to near its quantum ground state by tunneling injection of electrons from a scanning tunneling microscope tip. The interplay between two mechanisms for coupling the electronic and mechanical degrees of freedom results in a bias-voltage-dependent difference between the probability amplitudes for vibron emission and absorption during tunneling. For a bias voltage just below the Coulomb blockade threshold, we find that absorption dominates, which leads to cooling corresponding to an average vibron population of the fundamental bending mode of 0.2.
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| 14. |
- Santandrea, Fabio, 1981, et al.
(författare)
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Suppression of the stochastic fluctuations of suspended nanowires by temperature-induced single-electron tunneling
- 2011
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 13:10
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Tidskriftsartikel (refereegranskat)abstract
- We theoretically investigate the electromechanical properties of freely suspended nanowires that are in tunneling contact with the tip of a scanning tunneling microscope (STM) and two supporting metallic leads. The aim of our analysis is to characterize the fluctuations of the dynamical variables of the nanowire when a temperature drop is maintained between the STM tip and the leads, which are all assumed to be electrically grounded. By solving a quantum master equation that describes the coupled dynamics of electronic and mechanical degrees of freedom, we found that the stationary state of the mechanical oscillator has a Gaussian character, but that the amplitude of its root-mean square center-of-mass fluctuations is smaller than would be expected if the system were coupled only to the leads at thermal equilibrium.
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| 15. |
- Shekhter, Robert I., 1947, et al.
(författare)
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Electronic spin working mechanically
- 2014
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Ingår i: Fizika Nizkikh Temperatur. - 0132-6414 .- 1816-0328. ; 40:7, s. 775-792
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Tidskriftsartikel (refereegranskat)abstract
- A single-electron tunneling (SET) device with a nanoscale central island that can move with respect to the bulk source- and drain electrodes allows for a nanoelectromechanical (NEM) coupling between the electrical current through the device and mechanical vibrations of the island. Although an electromechanical "shuttle" in-stability and the associated phenomenon of single-electron shuttling were predicted more than 15 years ago, both theoretical and experimental studies of NEM-SET structures are still carried out. New functionalities based on quantum coherence, Coulomb correlations and coherent electron-spin dynamics are of particular current interest. In this article we present a short review of recent activities in this area.
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| 16. |
- Shekhter, Robert I., 1947, et al.
(författare)
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Electronic spin working mechanically (Review Article)
- 2014
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Ingår i: Low temperature physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 40:7, s. 600-614
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Tidskriftsartikel (refereegranskat)abstract
- A single-electron tunneling (SET) device with a nanoscale central island that can move with respect to the bulk source- and drain electrodes allows for a nanoelectromechanical (NEM) coupling between the electrical current through the device and mechanical vibrations of the island. Although an electromechanical “shuttle” instability and the associated phenomenon of single-electron shuttling were predicted more than 15 years ago, both theoretical and experimental studies of NEM-SET structures are still carried out. New functionalities based on quantum coherence, Coulomb correlations and coherent electron-spin dynamics are of particular current interest. In this article we present a short review of recent activities in this area.
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| 17. |
- Shekhter, Robert I., 1947, et al.
(författare)
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Mechano-electronic and electro-mechanical energy transfer in mesoscopic superconducting weak links
- 2012
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Ingår i: Comptes Rendus Physique. - : Elsevier BV. - 1878-1535 .- 1631-0705. ; 13:5, s. 426-439
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Forskningsöversikt (refereegranskat)abstract
- In this review we discuss how the nano-electro-mechanical properties of a superconducting weak link, formed by a suspended nanowire bridging two superconductors, can strongly affect mesoscopic effects in both the electronic and the mechanical subsystem. In particular we will discuss how quantum coherence and electron–electron (Coulomb) correlations may result in the possibility to resonantly redistribute energy between the electronic and mechanical degrees of freedom, allowing controllable switching between pumping and cooling of the nano-mechanical vibrations of the suspended nanowire. The two regimes of a given current and a given voltage supplied to the nano-electro-mechanical weak link is considered, resulting respectively in the possibility of ground-state cooling or resonant generation of nano-mechanical vibrations for realistic experimental parameters.
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| 18. |
- Shekhter, Robert I., 1947, et al.
(författare)
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Nanoelectromechanics of shuttle devices
- 2013
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Ingår i: Nanoelectromechanical Systems. - : Portico. - 2299-3169. ; 1, s. 1-25
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Tidskriftsartikel (refereegranskat)abstract
- A single-electron tunneling (SET) device with a nanoscale central island that can move with respect to the bulk sourceand drain electrodes allows for a nanoelectromechanical (NEM) coupling between the electrical current through the device and the mechanical vibrations of the island. Although the electromechanical “shuttle” instability and the associated phenomenon of single-electron shuttling were predicted more than 15 years ago, both theoretical and experimental studies of NEM-SET structures are still carried out. New functionalities based on quantum coherence, Coulomb correlations and coherent electron-spin dynamics are still of particular interest. In this article we present a short review of recent activities in this area.
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| 19. |
- Song, T., et al.
(författare)
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Self-sustained oscillations in nanoelectromechanical systems induced by Kondo resonance
- 2014
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the instability and dynamical properties of nanoelectromechanical systems represented by a single-electron device containing movable quantum dots attached to a vibrating cantilever via asymmetric tunnel contacts. The Kondo resonance in electron tunneling between the source and shuttle facilitates self-sustained oscillations originating from the strong coupling of mechanical and electronic/spin degrees of freedom. We analyze a stability diagram for the two-channel Kondo shuttling regime due to limitations given by the electromotive force acting on a moving shuttle, and find that the saturation oscillation amplitude is associated with the retardation effect of the Kondo cloud. The results shed light on possible ways to experimentally realize the Kondo-cloud dynamical probe by using high mechanical dissipation tunability as well as supersensitive detection of mechanical displacement.
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| 20. |
- Sonne, Gustav, 1982, et al.
(författare)
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Cooling of a suspended nanowire by an ac Josephson current flow
- 2010
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 104:22
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Tidskriftsartikel (refereegranskat)abstract
- We consider a nanoelectromechanical Josephson junction, where a suspended nanowire serves as a superconducting weak link, and show that an applied dc bias voltage can result in suppression of the flexural vibrations of the wire. This cooling effect is achieved through the transfer of vibronic energy quanta first to voltage-driven Andreev states and then to extended quasiparticle electronic states. Our analysis, which is performed for a nanowire in the form of a metallic carbon nanotube and in the framework of the density matrix formalism, shows that such self-cooling is possible down to the ground state of the flexural vibration mode of the nanowire.
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| 21. |
- Sonne, Gustav, 1982, et al.
(författare)
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Ground-State Cooling of a Suspended Nanowire through Inelastic Macroscopic Quantum Tunneling in a Current-Biased Josephson Junction
- 2011
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Ingår i: Physical Reveiw Letters. - 0031-9007 .- 1079-7114. ; 106:16
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate that a suspended nanowire forming a weak link between two superconductors can be cooled to its motional ground state by a supercurrent flow. The predicted cooling mechanism has its origins in magnetic field induced inelastic tunneling of the macroscopic superconducting phase associated with the junction. Furthermore, we show that the voltage drop over the junction is proportional to the average population of the vibrational modes in the stationary regime, a phenomenon which can be used to probe the level of cooling.
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| 22. |
- Sonne, Gustav, 1982, et al.
(författare)
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Voltage-driven superconducting weak link as a refrigerator for cooling of nanomechanical vibrations
- 2010
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Ingår i: Low Temperature Physics. - : AIP Publishing. - 1090-6517 .- 1063-777X. ; 36:10
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Tidskriftsartikel (refereegranskat)abstract
- We consider a new type of cooling mechanism for a suspended nanowire acting as a weak link between two superconductive electrodes. By applying a bias voltage over the system, we show that the system can be viewed as a refrigerator for the nanomechanical vibrations, where energy is continuously transferred from the vibrational degrees of freedom to the extended quasiparticle states in the leads through the periodic modulation of the inter-Andreev level separation. The necessary coupling between the electronic and mechanical degrees of freedom responsible for this energy-transfer can be achieved both with an external magnetic or electrical field, and is shown to lead to an effective cooling of the vibrating nanowire. Using realistic parameters for a suspended nanowire in the form of a metallic carbon nanotube we analyze the evolution of the density matrix and demonstrate the possibility to cool the system down to a stationary vibron population of ~0.1. Furthermore, it is shown that the stationary occupancy of the vibrational modes of the nanowire can be directly probed from the dc current responsible for carrying away the absorbed energy from the vibrating nanowire.
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| 23. |
- Vyurkov, V., et al.
(författare)
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Quantum computing based on space states without charge transfer
- 2010
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Ingår i: Physics Letters, Section A: General, Atomic and Solid State Physics. - : Elsevier BV. - 0375-9601. ; 374:33, s. 3285-3291
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Tidskriftsartikel (refereegranskat)abstract
- An implementation of a quantum computer based on space states in double quantum dots is discussed. There is no charge transfer in qubits during a calculation, therefore, uncontrolled entanglement between qubits due to long-range Coulomb interaction is suppressed. Encoding and processing of quantum information is merely performed on symmetric and antisymmetric states of the electron in double quantum dots. Other plausible sources of decoherence caused by interaction with phonons and gates could be substantially suppressed in the structure as well. We also demonstrate how all necessary quantum logic operations, initialization, writing, and read-out could be carried out in the computer. (C) 2010 Elsevier B.V. All rights reserved.
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