We will conduct experiments using semiconductor quantum dots with three objectives from the standpoints of control, observation, and transfer; namely, quantum error correction, Bell measurement based on quantum correlation measurements, and on-chip transfer of quantum information, respectively.
Semiconductor nanoassemblies allow the integration of quantum information devices due to the high degree of freedom of circuit design and are therefore suitable for the study of problems in control engineering, communications engineering, and observation for quantum information processing. We have successfully conducted 1- to 2-quantum-bit experiments using double-quantum-dot charge quantum bits (PRL, 2003) and electron spin quantum bits (Nature Phys, 2008), and achieved the measurement of electron spin correlations (Science, 2005) and high-accuracy measurement of charges (Science, 2006) using assemblies. We are undertaking studies in quantum cybernetics (physical properties experiments for control, observation, and communications) based on these achievements. The goals include (1) to achieve multi-bit control of quantum states and establish experimental techniques such as restoration of decoherence by quantum error correction and transfer of electron spin states, (2) to develop a theory of spin state control using the g-factor tensor, (3) to establish techniques for fast measurement of quantum bits by increasing the frequency of charge and capacity measurement and for 2-bit Bell measurement in the area of quantum state observation, (4) to theoretically study the transfer of wave packets (charge, spin) in quantum Hall edge channels in order to establish a technology for transfer between quantum bits that are distant from each other to some extent, and (5) to perform experiments on spin transfer by surface elastic waves and theoretical studies on decoherence of wave packet transfer and spin transfer. For open solicitation projects (one experimental and one theoretical), we would like to select those with a potential for expansion that are based on new perspectives (materials, measurement techniques, and theories). Based on these studies, we will be able to study quantum cybernetics using electrons in semiconductors as a medium and develop design guidelines for functional quantum information devices.
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