Pseudorandom binary injection of levitons for electron quantum optics

Abstract

The recent realization of single electron sources lets envision performing electron quantum optics experiments, where electrons can be viewed as flying qubits propagating in a ballistic conductor. To date, all electron sources operate in a periodic electron injection mode leading to energy spectrum singularities in various physical observables which sometime hide the bare nature of physical effects. To go beyond, we propose a spread-spectrum approach where electron flying qubits are injected in a non-periodic manner following a pseudo-random binary bit pattern. Extending the Floquet scattering theory approach from periodic to spread-spectrum drive, the shot noise of pseudo-random binary sequences of single electron injection can be calculated for leviton and non-leviton sources. Our new approach allows to disentangle the physics of the manipulated excitations from that of the injection protocol. In particular, the spread spectrum approach is shown to provide a better knowledge of electronic Hong Ou Mandel correlations and to clarify the nature of the pulse train coherence and the role of the dynamical orthogonality catastrophe for non-integer charge injection.

Hong-Ou-Mandel characterization of multiply charged Levitons

“…Further interesting developments could also involve the investigation of pseudorandom emission of Levitons, as recently proposed for the free fermion case [55]. Besides closing the conceptual gap between time-periodic injection and individual wave-packet emission -Holy Grail of EQO [56] -this newly proposed emission protocol opens important perspectives for the FQH case, as it promises to strongly magnify the side dip features discussed in the present text.…”

Crystallization of levitons in the fractional quantum Hall regime

“…In this context, observations of optical solitons in a non-linear background propagating with a spontaneously ordered temporal profile have been recently reported [1][2][3]. In the framework of electron quantum optics [4][5][6], a train of Lorentzian voltage pulses naturally emerges as the best candidate to realize the solid state analogue of optical solitons, namely robust ballistically propagating wave-packets carrying a single electron with no additional particle-hole pairs [7][8][9][10][11]. These minimal excitations, called Levitons, represent one of the most reliable tools to inject single electronic states into ballistic channels of meso-scale devices [12][13][14][15], and have been recently exploited to reproduce some famous quantum-optical experiments, such as Hanbury-Brown-Twiss (HBT) or Hong-Ou-Mandel (HOM) interferometry, at the fermionic level [16,17].…”

“…These minimal excitations, called Levitons, represent one of the most reliable tools to inject single electronic states into ballistic channels of meso-scale devices [12][13][14][15], and have been recently exploited to reproduce some famous quantum-optical experiments, such as Hanbury-Brown-Twiss (HBT) or Hong-Ou-Mandel (HOM) interferometry, at the fermionic level [16,17]. These fascinating experimental results open up the possibility of exploiting Levitons as flying qubits with appealing applications for quantum information processing [11,18]. Moreover, similarly to solitons, q different Levitons travel unhindered along one-dimensional electronic edge states and can be controllably superimposed, thus forming manybody states called multi-electron Levitons or, simply, q-Levitons [18,19].…”

Quantum computing with quantum-Hall edge state interferometry

“…The on-demand generation of pure quantum excitations is crucial for the controlled propagation of single carriers in ESs, but it is particularly difficult for a system of fermions where an external voltage bias affects the states below the Fermi sea, thus resulting in a complex superposition of electrons and holes. A protocol to inject single-electrons in edge channels was first proposed by Levitov [9,70,71], who suggested that it is possible to generate a minimal excitation, later named "Leviton", containing only one electron charge and no holes, with a properly time-dependent perturbation V (t) of Lorentzian shape:…”