A solid-state two-qubit quantum gate was recently proposed that might be made in a silicon fabrication plant in the near future. In this class of device, entanglement between two quantum bits is controlled by a change from a largely unentangled ground electronic state to an excited state in which useful entanglement can be produced. Such gates have potential advantages, both because they exploit known solid-state behaviour and they separate the storage and manipulation of quantum information. It is important that the excitation step does not create decoherence. We analyse a type of gate proposed before, in which the excitation involves a control electron that interacts with the qubit spins in the excited state. The dynamics of an idealized (but fairly general) gate of this type show that it can be operated to produce a standard two-qubit entangling state.
We propose an experiment to observe interference of a single electron as it is transported along two parallel quasi-one-dimensional channels trapped in a single minimum of a travelling periodic electric field. The experimental device is a modification of the surface acoustic wave (SAW) based quantum processor. Interference is achieved by creating a superposition of spatial wavefunctions between the two channels and inducing a relative phase shift via either a transverse electric field or a magnetic field. The interference can be used to estimate the decoherence time of an electron in this type of solid-state device.Constructing a solid-state single-electron interferometer poses many challenges, especially single-electron transport through the device. Recent experiments on electron interferometers [1,2] and double quantum dots [3] have demonstrated interference, but do not deal with single electrons. These experiments have to take into account many-particle effects, the behaviour of electrons as quasi-particles, and the validity of the application of theories such as Fermi liquid theory. Besides not showing true single particle interference, these factors obscure the fundamental electron coherence time, which is of crucial importance for many prospective solid state quantum information processing schemes [4,5,6,7,8].Electron quantization using surface acoustic waves (SAW), originally studied in the context of current standards [9,10], has recently lead to a proposal for the implementation of a quantum processor in the solid-state that uses this mechanism [11]. Advantages of the proposed SAW devices include the unique feature of creating a completely polarised initial state and of making ensemble measurements over billions of identical computations. Additionally, these systems are similar to quantum dots, but have the advantage that manipulation of qubits can be done with static potentials on surface gates without the need for expensive high-frequency pulse generation [3]. Furthermore, the mechanism of SAW transport eliminates the problem of backscattering from discontinuities in the electron trajectory which also detracts from the ideal interferometry experiment [22] [23]. This opens up the range of mechanisms for inducing relative phase shifts required to observe interference fringes.The acoustoelectric devices we consider in this paper are fabricated on modulation doped GaAs-AlGaAs heterostructures. Because GaAs is a piezoelectric material, applying a radio-frequency potential difference between a pair of interdigitated transducers produces vibrations that propagate through the structure as longitudinal waves (SAWs), which in turn induce an electrostatic potential. The SAWs then travel across the 2-dimensional electron gas and through a mesa patterned with surface gates that define two parallel quasi-onedimensional channels. By altering the static potential on the surface gates it is possible to trap a single electron in each SAW potential minimum in each of the two channels with an accuracy greater than 1 part...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.