University of Cambridge > > Semiconductor Physics Group Seminars > Measurement and control of electron wavepackets from a single-electron source (SP Workshop)

Measurement and control of electron wavepackets from a single-electron source (SP Workshop)

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Circuits that can perform triggered emission, coherent control and sensitive detection of single electrons are highly desirable for quantum information processing [1] and studies of the fermionic quantum properties of electrons, such as single-electron analogs of quantum optics [2]. Semiconductor single-electron pumps [3] are a promising source of single electrons ``on demand’’ for use in these single-electron circuits. For these applications it is important to understand and control the properties of the emitted electrons. Here we study the time and energy distributions of single-electrons and pairs of electrons emitted by a semiconductor tunable-barrier quantum-dot electron pump. Single electrons emitted by the pump are guided by edge states to an energy-selective detector barrier [4]. By controlling the barrier transparency on picosecond timescales, we image the electron wavepackets in the time and energy domain, with a temporal resolution of 30 ps. Using an arbitrary waveform generator (AWG), we study the link between the electron time and energy distributions and the shape of the rf waveform driving the pump. We find that the digital nature of the AWG waveform gives rise to distinct features in the electron energy distribution, which we use to develop a tunnelling model of the electron emission process [5] and to pin-point the electron emission time within the pumping cycle. Using these insights, we show that by engineering the pump drive waveform we can manipulate the electron wavepackets, using the example of controlling the time and energy difference between a pair of electrons. This technique could be particularly useful when combined with studies of the electron partitioning noise [6], to determine the origins of correlations between the pumped electrons.

[1] D. Loss and D.P. DiVincenzo, Phys. Rev. A 57 , 120 (1998).

[2] E. Boquillon et al, Phys. Rev. Lett. 108, 196803 (2012).

[3] M.D. Blumenthal et al, Nature Physics 3, 343 (2007).

[4] J.D. Fletcher et al, Phys. Rev. B 111 , 216807 (2013).

[5] V. Kashcheyevs and B. Kaestner, Phys. Rev. Lett. 104, 186805 (2010).

[6] N. Ubbelohde et al, Nat. Nano. 10, 46 (2015).

This talk is part of the Semiconductor Physics Group Seminars series.

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