Accession Number : ADA623719


Title :   Few-electron Qubits in Silicon Quantum Electronic Devices


Descriptive Note : Doctoral thesis


Corporate Author : PRINCETON UNIV NJ


Personal Author(s) : Wang, Ke


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a623719.pdf


Report Date : Sep 2014


Pagination or Media Count : 116


Abstract : Artificial two-level quantum systems are widely investigated as the fundamental building blocks of future quantum computers. These quantum bits (qubits) can be realized in many solid state systems, including Josephson junction based devices, nitrogen vacancy centers in diamond, and electron spins in semiconductor quantum dots. Among these systems, Si is very promising since it can be isotopically purified to eliminate random fluctuating hyperfine fields from lattice nuclei, leading to ultra-long quantum coherence times. However, lower heterostructure quality, higher electron effective mass and valley degeneracy present many challenges in realizing high quality qubits in Si. This thesis demonstrates consistent realization of robust single-electron silicon qubits with high yield. With optimized device designs and DC/RF measurement techniques developed at Petta lab in Princeton University, we have achieved versatile quantum control of a single electron, as well as sensitive read-out of its quantum state. By applying microwave radiation to the gate electrodes, we can probe the energy level structure of the system with 1 mu-eV resolution. We apply bursts of microwave radiation to extract the qubit lifetime, T1 . By experimentally tuning the qubit, we demonstrate a four order of magnitude variation of T1 with gate voltage. We show that our experimental results are consistent with a theory that takes into account phonon-mediated charge relaxation.


Descriptors :   *ELECTRON SPIN RESONANCE , *QUANTUM COMPUTING , COHERENCE , DIAMONDS , DIRECT CURRENT , ELECTRODES , ENERGY LEVELS , GALLIUM ARSENIDES , GATES(CIRCUITS) , HETEROGENEITY , HYPERFINE STRUCTURE , ISOTOPES , JOSEPHSON JUNCTIONS , LATTICE DYNAMICS , MICROWAVES , MODULAR CONSTRUCTION , NITROGEN , NUCLEI , OPTIMIZATION , PURIFICATION , QUANTUM DOTS , RADIOFREQUENCY , RELAXATION , SEMICONDUCTORS , SILICON , SYSTEMS ENGINEERING , THESES , VOLTAGE , WAFERS


Subject Categories : Physical Chemistry
      Electrical and Electronic Equipment
      Quantum Theory and Relativity
      Solid State Physics


Distribution Statement : APPROVED FOR PUBLIC RELEASE