Quantized acoustoelectric current transport through a static quantum dot using a surface acoustic wave

Fletcher, Nick; Ebbecke, J.; Janssen, T. J. B. M.; Ahlers, F. J.; Pepper, M.; Beere, Harvey E.; Ritchie, D. A.

doi:10.1103/physrevb.68.245310

Cited by 66 publications

(50 citation statements)

References 29 publications

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“…Numerous works have studied mesoscopic pumps both theoretically 1,2,3,4,5 as well as experimentally. 6,7,8,9,10 The established framework to calculate the pumped charge through a mesoscopic scatterer is based on the dynamical scattering approach. 1,11 This approach can be applied when the Coulomb interaction can be neglected or treated within the Hartree approximation.…”

Section: Introductionmentioning

confidence: 99%

Adiabatic charge and spin pumping through quantum dots with ferromagnetic leads

2008

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We study adiabatic pumping of electrons through quantum dots attached to ferromagnetic leads. Hereby we make use of a real-time diagrammatic technique in the adiabatic limit that takes into account strong Coulomb interaction in the dot. We analyze the degree of spin polarization of electrons pumped from a ferromagnet through the dot to a nonmagnetic lead (N-dot-F) as well as the dependence of the pumped charge on the relative leads' magnetization orientations for a spinvalve (F-dot-F) structure. For the former case, we find that, depending on the relative coupling strength to the leads, spin and charge can, on average, be pumped in opposite directions. For the latter case, we find an angular dependence of the pumped charge, that becomes more and more anharmonic for large spin polarization in the leads.

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Section: Introductionmentioning

confidence: 99%

Adiabatic charge and spin pumping through quantum dots with ferromagnetic leads

2008

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“…Spin qubits in SAW-dots have been investigated as a possible realisation of a quantum computer 16,17,18 and recently it was demonstrated theoretically that maximal entanglement can arise from the interaction between a SAW spin qubit and a spin qubit trapped in a static dot (SD), embedded in the depleted channel along which the SAW propagates 19 . Experimentally the interaction between SAW-dots and a SD has been examined mainly in terms of the acoustoelectric current 20,21,22 though the main goal is the fabrication of a SAW-based device for quantum information processing 23 .…”

Section: Pacs Numbersmentioning

confidence: 99%

Generation of Einstein-Podolsky-Rosen pairs and interconversion of static and flying electron spin qubits

et al. 2007

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We propose a method of generating fully entangled electron spin pairs using an open static quantum dot and a moving quantum dot, realised by the propagation of a surface acoustic wave (SAW) along a quasi-one-dimensional channel in a semiconductor heterostructure. In particular, we consider a static dot (SD) loaded with two interacting electrons in a singlet state and demonstrate a mechanism which enables the moving SAW-dot to capture and carry along one of the electrons, hence yielding a fully entangled static-flying pair. We also show how with the same mechanism we can load the SD with one or two electrons which are initially carried by a SAW-induced dot. The feasibility of realizing these ideas with existing semiconductor technology is demonstrated and extended to yield flying or static pairs that are fully entangled and arbitrary interconversion of static and flying electron spin qubits. PACS numbers:Einstein-Podolsky-Rosen (EPR) particle pairs are spatially separated and fully entangled particles such as photons or electrons 1 . A spin entangler system, which is a system capable of generating EPR spin pairs, is of fundamental importance not only in the field of quantum computation but also in quantum mechanics for testing nonlocal correlations 1 . In addition the ability to interconvert static and flying qubits is a basic requirement for quantum computation and communication in general 2 . In the solid state both the creation of an entangler for massive particles and interconversion of qubits are hard tasks since the process of generation and detection must take place in a controlled way and in a much shorter time than typical decoherence times. Electron spin qubits in semiconductors are particularly promising since their decoherence times can be quite long, e.g. ∼100 ns in GaAs 3 , and a number of entangler schemes have been studied, at least theoretically. These for example include EPR pairs via Coulomb scattering 4 , a triple quantum dot structure 5,6 , a three-port dot 7 , a superconductor attached to a double dot 8 and a turnstile double dot device 9,10,11,12 .As has been demonstrated experimentally the propagation of a surface acoustic wave (SAW) along a depleted one-dimensional channel in a GaAs/AlGaAs twodimensional electron gas (2DEG) results in the formation of moving quantum dots 13,14 . The heterostructure confines the electrons in the plane of the quantum well, whereas lateral confinement in one direction is due to the channel and in the other direction to the induced time dependent electrostatic potential which accompanies the SAW mechanical propagation. The moving SAW-induced dots can capture electrons from the 2DEG and transport them through the channel. Under a regime of parameters of SAW power and gate voltage the number of transported electrons by the SAW can be controlled down to one yielding a quantized acoustoelectric current of nA with an accuracy of five parts in 10 4 . 13,14,15 In general, this current can be expressed as nef , where n = 1, 2..., is the average number of electrons in...

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“…Any significant discrepancy will prompt further experimental and theoretical work. The closure of the QMT, at the required uncertainty of one part in 10 8 or less, should be assisted by improvements in SQUIDs, microlithography techniques and new SET devices which could generate accurate currents as high as 100 pA. Ideas currently under investigation for the implementation of a higherfrequency-locked current source include improved SETSAW devices [111] and superconducting Cooper pair pumps as a generalization of a single electron pump [112].…”

Section: Future Trends and Conclusionmentioning

confidence: 99%