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Simultaneous readout of two charge qubits

Jian Li (Institutionen för mikroteknologi och nanovetenskap, Tillämpad kvantfysik) ; Göran Johansson (Institutionen för mikroteknologi och nanovetenskap, Tillämpad kvantfysik)
Physical Review B Vol. 75 (2007), 085312,
[Artikel, refereegranskad vetenskaplig]

We consider a system of two solid state charge qubits, coupled to a single readout 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.

Denna post skapades 2008-01-02. Senast ändrad 2014-09-02.
CPL Pubid: 64114


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Institutioner (Chalmers)

Institutionen för mikroteknologi och nanovetenskap, Tillämpad kvantfysik


Mesoskopisk fysik

Chalmers infrastruktur