| 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. |
- Bahrova, O. M., et al.
(författare)
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Cooling of nanomechanical vibrations by Andreev injection
- 2022
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Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 48:6, s. 476-482
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Tidskriftsartikel (refereegranskat)abstract
- A nanoelectromechanical weak link composed of a carbon nanotube suspended between two normal electrodes in a gap between two superconducting leads is considered. The nanotube is treated as a movable single level quantum dot in which the position-dependent superconducting order parameter is induced due to the Cooper pair tunneling. We show that electron tunneling processes significantly affect the state of the mechanical subsystem. We found that at a given direction of the applied voltage between the electrodes, the stationary state of the mechanical subsystem has a Boltzmann form with an effective temperature dependent on the parameters of the device. As this takes place, the effective temperature can reach significantly small values (cooling effect). We also demonstrate that nanotube fluctuations strongly affect the dc current through the system. The latter can be used to probe the predicted effects in an experiment. Published under an exclusive license by AIP Publishing.
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| 3. |
- Bahrova, O. M., et al.
(författare)
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Entanglement between charge qubit states and coherent states of nanomechanical resonator generated by ac Josephson effect
- 2021
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Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 47:4, s. 287-293
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Tidskriftsartikel (refereegranskat)abstract
- We considered a nanoelectromechanical system consisting of a movable Cooper-pair box qubit, which is subject to an electrostatic field, and coupled to the two bulk superconductors via tunneling processes. We suggest that qubit dynamics is related to that of a quantum oscillator and demonstrate that a bias voltage applied between superconductors generates states represented by the entanglement of qubit states and coherent states of the oscillator if certain resonant conditions are fulfilled. It is shown that a structure of this entanglement may be controlled by the bias voltage in a way that gives rise to the entanglement incorporating so-called cat-states—the superposition of coherent states. We characterize the formation and development of such states analyzing the entropy of entanglement and corresponding Wigner function. The experimentally feasible detection of the effect by measuring the average current is also considered.
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| 4. |
- Bahrova, O. M., et al.
(författare)
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Nanomechanics driven by the superconducting proximity effect
- 2022
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 24:3
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Tidskriftsartikel (refereegranskat)abstract
- We consider a nanoelectromechanical weak link composed of a carbon nanotube suspended above a trench in a normal metal electrode and positioned in a gap between two superconducting leads. The nanotube is treated as a movable single-level quantum dot (QD) in which the position-dependent superconducting order parameter is induced as a result of Cooper pair tunneling. We show that in such a system, self-sustained bending vibrations can emerge if a bias voltage is applied between normal and superconducting electrodes. The occurrence of this effect crucially depends on the direction of the bias voltage and the relative position of the QD level. We also demonstrate that the nanotube vibrations strongly affect the dc current through the system, a characteristic that can be used for the direct experimental observation of the predicted phenomenon.
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| 5. |
- Eriksson, Martin, 1989, et al.
(författare)
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Nonresonant high frequency excitation of mechanical vibrations in a graphene based nanoresonator
- 2015
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 17
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Tidskriftsartikel (refereegranskat)abstract
- We theoretically analyze the dynamics of a suspended graphene membrane which is in tunnel contact with grounded metallic electrodes and subjected to ac-electrostatic potential induced by a gate electrode. It is shown that for such a system the retardation effects in the electronic subsystem generate an effective pumping for the relatively slow mechanical vibrations if the driving frequency exceeds the inverse charge relaxation time. Under this condition there is a critical value of the driving voltage amplitude above which the pumping overcomes the intrinsic damping of the mechanical resonator, leading to a mechanical instability. This nonresonant instability is saturated by nonlinear damping and the system exhibits self-sustained oscillations of relatively large amplitude.
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| 6. |
- Eriksson, Martin, 1989, et al.
(författare)
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Selective nonresonant excitation of vibrational modes in suspended graphene via vibron-plasmon interaction
- 2015
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Ingår i: 2D Materials. - : IOP Publishing. - 2053-1583. ; 2:4
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Tidskriftsartikel (refereegranskat)abstract
- We theoretically study a doped graphene ribbon suspended over a trench and subject to an ac-electrical field polarized perpendicularly to the graphene plane. In such a system, the external ac-field is coupled to the relatively slow mechanical vibrations via plasmonic oscillations in the isolated graphene sheet. We show that the electrical field generates an effective pumping of the mechanical modes. It is demonstrated that in the case of underdamped plasma oscillation, a peculiar kind of geometrical resonance of the mechanical and plasma oscillations appear. The efficiency of pumping significantly increases when the wavenumber of the mechanical mode is in close agreement with the wavenumber of the plasma waves. The intensity of the pumping increases with the wavenumber of the mode. This phenomenon allows selective actuation of different mechanical modes, although the driving field is homogeneous.
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| 7. |
- Fedorets, D., et al.
(författare)
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Quantum precursor of shuttle instability
- 2004
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Ingår i: Fundamental problems of mesoscopic physics / Lerner, I.V. , Altshuler, B.L. , Gefen, Y.. ; , s. 65-73
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 8. |
- Fedorets, Dmytro, 1976, et al.
(författare)
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Quantum shuttle phenomena in a nanoelectromechanical single-electron transistor
- 2004
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 92
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Tidskriftsartikel (refereegranskat)abstract
- An analytical analysis of quantum shuttle phenomena in a nanoelectromechanical single-electron transistor has been performed in the realistic case, when the electron tunneling length is much greater than the amplitude of the zero point oscillations of the central island. It is shown that when the dissipation is below a certain threshold value, the vibrational ground state of the central island is unstable. The steady state into which this instability develops is studied. It is found that if the electric field E between the leads is much greater than a characteristic value E-q, the quasiclassical shuttle picture is recovered, while if E0) shuttle vibrations.
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| 9. |
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| 10. |
- Gorelik, Leonid, 1952, et al.
(författare)
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Coulomb promotion of spin-dependent tunneling
- 2005
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 95:11
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Tidskriftsartikel (refereegranskat)abstract
- We study transport of spin-polarized electrons through a magnetic single-electron transistor (SET) in the presence of an external magnetic field. Assuming the SET to have a nanometer size central island with a single-electron level we find that the interplay on the island between coherent spin-flip dynamics and Coulomb interactions can make the Coulomb correlations promote rather than suppress the current through the device. We find the criteria for this new phenomenon-Coulomb promotion of spin-dependent tunneling-to occur. © 2005 The American Physical Society.
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