6533b7cefe1ef96bd125711b
RESEARCH PRODUCT
Simultaneous readout of two charge qubits
Jian LiGöran Johanssonsubject
PhysicsFlux qubitCharge qubitCondensed Matter - Mesoscale and Nanoscale PhysicsFOS: Physical sciencesOne-way quantum computerCondensed Matter::Mesoscopic Systems and Quantum Hall EffectCondensed Matter PhysicsElectronic Optical and Magnetic MaterialsPhase qubitComputer Science::Emerging TechnologiesQuantum error correctionQubitQuantum mechanicsMesoscale and Nanoscale Physics (cond-mat.mes-hall)Superconducting quantum computingTrapped ion quantum computerdescription
We consider a system of two solid state charge qubits, coupled to a single read-out device, consisting of a single-electron transistor (SET). The conductance of each tunnel junction is influenced by its neighboring qubit, and thus the current through the transistor is determined by the qubits' state. The full counting statistics of the electrons passing the transistor is calculated, and we discuss qubit dephasing, as well as the quantum efficiency of the readout. The current measurement is then compared to readout using real-time detection of the SET island's charge state. For the latter method we show that the quantum efficiency is always unity. Comparing the two methods a simple geometrical interpretation of the quantum efficiency of the current measurement appears. Finally, we note that full quantum efficiency in some cases can be achieved measuring the average charge of the SET island, in addition to the average current.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2006-11-06 | Physical Review B |