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SUMMARY:Toward the realization of the quantum ampere with silicon nanoelec
 tronics - Dr Alessandro Rossi\, University of Cambridge\, Microelectronics
  Group
DTSTART:20160523T131500Z
DTEND:20160523T141500Z
UID:TALK66244@talks.cam.ac.uk
CONTACT:Teri Bartlett
DESCRIPTION:On-demand transfer of single electrons at sub-nanosecond times
 cales via semiconductor quantum dots has attracted great interest in the b
 road context of quantum technologies. While this technique has been initia
 lly developed to enable a quantum realization of the unit ampere\, more re
 cently it has proved to be key for the emerging field of fermionic quantum
  optics and it could become instrumental for the upscaling of future solid
 -state quantum computers.\n\nAt present\, charge transfers with the lowest
  uncertainty have been achieved with GaAs quantum dot-based pumps [1]. How
 ever\, in order to optimally operate these devices\, demanding experimenta
 l conditions are required\, such as very large perpendicular magnetic fiel
 d\, millikelvin temperature\, and\, in some case\, specially tailored wave
 form of the driving signal [2]. Silicon implementations promise to signifi
 cantly simplify these operation requirements in light of the mature metal-
 oxide-semiconductor (MOS) technology offering excellent control of the ele
 ctrostatic confinement.\n\nIn this talk\, I will discuss our latest result
 s with silicon MOS quantum dot- based pumps. By improving upon a previous 
 device design [3]\, we have achieved a tighter electrostatic confinement a
 nd charging energies in excess of 30 meV in the few-electron regime. This 
 has resulted in fast and precise single-electron transfers at temperature 
 as high as 4K and frequency in excess of 3.5 GHz by using a single-harmoni
 c driving signal. The robustness of the pumping mechanism is confirmed by 
 the evaluation of random uncertainties below 2 parts per million for varia
 tions of the experimental gate voltages of several tens of mV. Finally\, I
  will discuss directions towards the integration of superconductor charge 
 sensors and silicon pumps for charge counting experiments [4]\, as well as
  the realization of ambipolar devices to compare and contrast pumping with
  electrons and holes.\n\n[1] F. Stein et al.\, Appl. Phys. Lett. 107\, 103
 501 (2015).\n[2] S.P. Giblin et al.\, Nature Comm. 3\, 930 (2012).\n[3] A.
  Rossi et al.\, Nano Lett. 14\, 3405 (2014).\n[4] T. Tanttu et al. New J. 
 Phys. 17\, 103030 (2015).\n
LOCATION:Mott Seminar Room (Mott Building Room 531)\, Cavendish Laboratory
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