Static and Dynamic Properties of Flying Spin Qubits

Noriaki Horiuchi

Deniz Türkpençe

Amritesh Sharma, Ashwin A. Tulapurkar

We consider a system of static spin qubits embedded in a one-dimensional spin-coherent channel and develop a scheme to readout the state of one and two qubits separately. We use unpolarized flying qubits for this purpose that scatter off from the static qubits due to localized Heisenberg exchange interaction. Analyzing the transmission coefficient as a function of density matrix elements along with additional unitary gates we reconstruct the state of static qubits.

David Peter Divincenzo

Yuting Ping, J. H. Jefferson, Brendon W. Lovett

We show that the state of a flying qubit may be transferred to a chain of identical, (near) ferromagnetically polarised, but non-interacting, static spin-1/2 particles in a passive way. During this process the flying qubit is coherently polarised, emerging in the direction of the majority static spins. We also show that this process is reversible for at least two flying qubits injected sequentially and thus has the potential to be exploited as a passive quantum memory to encode the flying qubits without the necessity of resetting between successive encoding operations. We show that the quantum information may be spread over many static spins in the memory chain, making the mechanism resistent to spin decoherence and other imperfections. Among some potential architectures, we discuss implementing the memory in a photonic waveguide embedded with quantum dots, which is resilient to various possible errors.

G. Giavaras, J. H. Jefferson, M. Fearn +1 more

We propose a method of generating fully entangled electron spin pairs using an open static quantum dot and a moving quantum dot, realized 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.