Manipulation of an exciton qubit by ultrafast electronics

In our recent work we report on the coherent phase manipulation of quantum dot excitons by electric means. The phase manipulation was performed and quantified in a Ramsey experiment, where ultrafast electric detuning of the exciton energy is performed synchronous to double pulse ps laser excitation.

For the experimental realization we used low capacitance single quantum dot photodiodes which were electrically controlled by ultrafast, custom designed BiCMOS chips.

Original work: Widhalm, A.; Mukherjee, A.; Krehs, S.; Sharma, N.; Kölling, P.; Thiede, A.; Reuter, D.; Förstner, J.; Zrenner, A. (2018): Ultrafast electric phase control of a single exciton qubit. In: APPLIED PHYSICS LETTERS 112 (11), S. 111105. DOI: <link http: www.dx.doi.org>10.1063/1.5020364.

Protocol for the coherent optoelectronic preparation of an arbitrary quantum state in an exciton qubit and corresponding representation on the Bloch sphere. For the experiment single quantum dot photodiodes have been connected to BiCMOS chips working at T=4.2 K.