Flying Electron Qubits

The control of single electrons has been a subject of intense research for several decades. A typical example is the definition of the electrical current of our SI unit system, which relies on a precise control and measurement of the electron charge over time. Recently, the concept of flying electron qubits has emerged [1], where the charge [2] or spin [3] degree of freedom of an electron are used as qubits that are manipulated and transported through electronic circuits. These qubits are particularly interesting because they can be controlled using simple electromagnetic fields. However, there are still challenges to be overcome in the implementation of flying electron qubits, including high-fidelity control of individual electrons and the design of scalable quantum circuits.

In this talk, I will introduce the different approaches to achieve this ambitious goal and present the latest advances in the field of single electron transport. We will present two different but complementary methods in which a single charge carrier is transported through a quantum electronic circuit. In the first example, the electron is isolated from the Fermi sea and transported using a sound wave [2]. We will show that electrons can be transported with a fidelity well above 99% [4,5] and collision experiments at the single particle level are now possible [6]. In a second approach, the electron propagates along the surface of the Femi sea in the form of an ultrashort electron wave packet [7]. We find that, contrary to naive expectation, the coherence of the system is significantly improved when the temporal width of the wave packet is reduced. This opens a path for new and exciting quantum experiments at the single electron level.

References:
[1] Bäuerle et al., Rep. Prog. Phys. 81, 056503 (2018)
[2] Hermelin et al., Nature 477, 435–438 (2011) ; McNeil et al., Nature 477, 439–442 (2011)
[3] Jadot et al., Nat. Nanotechnol. 16, 570–575 (2021)
[4] Takada et al., Nat. Commun. 10, 4557 (2019)
[5] Wang et al., Phys. Rev. X 12, 031035 (2022); highlight in Physics: physics.aps.org/articles/v15/132
[6] Wang et al., accepted for publication in Nature Nanotechnology, arxiv.org/abs/2210.03452
[7] J. Dubois, et al., Nature 502, 659-663 (2013) ; Roussely et al., Nature Communications 9 2811 (2018)