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

Abstract

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...

Classical information transfer between distant quantum dots using individual electrons in fast moving quantum dots

“…In addition, the ability to trigger the transfer on the nanosecond timescale and the inherent speed of the transport make it faster than the spin coherence time T * 2 . Further developments in the directions of routing [37] using several SAW beams or using the transport itself to manipulate the electron spin via the spin orbit interaction and/or shaped gates [42] will be other additions to the growing toolbox in the fields of spintronics, electron-spin qubits [78], and quantum optics with flying electrons [79,80].…”

One-step generation of Bell state on nonlocal acoustics wave resonators assisted by nitrogen-vacancy center ensembles

“…Among the quantum systems, AWR performs a good quantum information carrier as the quality factor of AWR has been increased to 10 11 [45], which means it can store phonons with a low leakage rate. Some basic tasks of QIP [24,[46][47][48][49][50][51][52] on AWR have been studied and the research on the coupling between an AWR and other quantum systems [44,[53][54][55][56][57][58][59][60] has attracted much attention. In 2010, O'Connell et al [46] achieve the single-phonon control of an AWR with the superconducting qubit.…”

Acoustoelectric current in graphene due to electron deformation potential and piezoelectric phonon couplings

“…The coupling of acoustic phonons with electrons is a phenomenon that serves both as a source of exciting physics and as a resource for novel device applications that emerge from time to time [1]. Phonons or phonon based mechanisms are an integral part of many modern technologies in which phonons can be manipulated in materials for novel device applications, including the promising functionalities for carrying and processing quantum information [1][2][3][4][5][6][7][8]. This has given rise to a competing fast emerging field of phononics in parallel to electronics and photonics.…”