Generation of energy selective excitations in quantum Hall edge states

Leicht, C.; Mirovsky, P.; Kaestner, B.; Hohls, Frank; Kashcheyevs, Vyacheslavs; Kurganova, E. V.; Zeitler, U.; Weimann, Thomas; Pierz, K.; Schumacher, H. W.

doi:10.1088/0268-1242/26/5/055010

Cited by 66 publications

(89 citation statements)

References 29 publications

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“…(1) and (3) in our paper to the instantaneous current formulae derived in Ref. 23 for a periodically modulated mesoscopic system.…”

Section: Appendix A: Relation To Floquet Formalismmentioning

confidence: 78%

“…A prototypical realization for the model is a small near-empty electrostatically defined quantum dot with large level spacing and charging energy, as in, e.g. [3,17]. A linear ramp of voltage V 1 (t) on a gate that defines the tunnel barrier between the source and the quantum dot creates the timedependencies (5) and (6) while a static voltage V 2 on another gate can be used to tune the decoupling energy, ε c = −αV 2 ∆ ptb + const.…”

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confidence: 99%

“…Successful demonstration of electron-on-demand sources based on electrostatic modulation of nanoelectronic circuit elements such as dynamic quantum dots [1][2][3] or mesoscopic capacitors [4,5] has offered a prospect of building an electronic analog of few-photon quantum optics [6] that exploits the particle-wave duality and entanglement of individual elementary excitations in a Fermi sea [7][8][9][10]. This ambitious goal is complemented by a long-standing challenge in quantum metrology [11] to untie the definition of ampere from the mechanical units of SI [12] and implement a current standard based on direct counting of discrete charge carriers.…”

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confidence: 99%

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Quantum Fluctuations and Coherence in High-Precision Single-Electron Capture

Kashcheyevs

Timoshenko

2012

Phys. Rev. Lett.

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The phase of a single quantum state is undefined unless the history of its creation provides a reference point. Thus quantum interference may seem hardly relevant for the design of deterministic single-electron sources which strive to isolate individual charge carriers quickly and completely. We provide a counterexample by analyzing the non-adiabatic separation of a localized quantum state from a Fermi sea due to a closing tunnel barrier. We identify the relevant energy scales and suggest ways to separate the contributions of quantum non-adiabatic excitation and backtunneling to the rare non-capture events. In the optimal regime of balanced decay and non-adiabaticity, our simple electron trap turns into a single-lead Landau-Zener-backtunneling interferometer, revealing the dynamical phase accumulated between the particle capture and leakage. The predicted "quantum beats in backtunneling" may turn the error of a single-electron source into a valuable signal revealing essentially non-adiabatic energy scales of a dynamic quantum dot.PACS numbers: 73.63. Kv, 73.23.Hk, 73.21.La Successful demonstration of electron-on-demand sources based on electrostatic modulation of nanoelectronic circuit elements such as dynamic quantum dots [1][2][3] or mesoscopic capacitors [4,5] has offered a prospect of building an electronic analog of few-photon quantum optics [6] that exploits the particle-wave duality and entanglement of individual elementary excitations in a Fermi sea [7][8][9][10]. This ambitious goal is complemented by a long-standing challenge in quantum metrology [11] to untie the definition of ampere from the mechanical units of SI [12] and implement a current standard based on direct counting of discrete charge carriers. So far the overlap between these research directions [13,14] has been rather limited arguably because metrological applications strive to maximize the particle nature of on-demand excitations.Optimizing the trade-off between speed and accuracy of single-electron isolation [2] does require consideration of quantum error mechanisms such as non-adiabatic excitation [15][16][17] or backtunneling [18][19][20][21]. However, these effects have been hard to differentiate experimentally owing to complexity of non-equilibrium many-particle quantum dynamics [22] and experimental challenges in exercising high-speed control of the electrostatic landscape. The quantum phase of the captured particle has been considered thus far as inconsequential for accuracy and inaccessible for measurement unless the particle is ejected into a separate interferometer [10].In this work, we propose a new type of interferometry to measure and thus control the non-equilibrium energy scales governing the decoupling of a dynamic quantum dot from a Fermi sea. Remarkably, our approach requires neither multiple spatial paths [9,10] nor noise measurements [8,22,23], relying instead on quantum beats in spontaneous emission of electrons back to the source lead. Using a generic [22,24] effective single-particle model we predict an interfer...

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“…(1) and (3) in our paper to the instantaneous current formulae derived in Ref. 23 for a periodically modulated mesoscopic system.…”

Section: Appendix A: Relation To Floquet Formalismmentioning

confidence: 78%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Quantum Fluctuations and Coherence in High-Precision Single-Electron Capture

Kashcheyevs

Timoshenko

2012

Phys. Rev. Lett.

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“…Electrons are emitted from a tunable-barrier single-electron pump [26][27][28] approximately 100 meV above the Fermi energy [13,29]. These electrons are injected into an edge where the background two-dimensional electron gas (2DEG) is depleted to avoid the influence of electron-electron interactions.…”

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confidence: 99%

Time-of-Flight Measurements of Single-Electron Wave Packets in Quantum Hall Edge States

et al. 2016

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We report time-of-flight measurements on electrons traveling in quantum Hall edge states. Hot-electron wave packets are emitted one per cycle into edge states formed along a depleted sample boundary. The electron arrival time is detected by driving a detector barrier with a square wave that acts as a shutter. By adding an extra path using a deflection barrier, we measure a delay in the arrival time, from which the edgestate velocity v is deduced. We find that v follows 1=B dependence, in good agreement with theẼ ×B drift. The edge potential is estimated from the energy dependence of v using a harmonic approximation. DOI: 10.1103/PhysRevLett.116.126803 Electronic analogues of photonic quantum-optics experiments, so-called "electron quantum optics," can be performed using the beams of single-electron wave packets. The demonstration of entanglement and multiparticle interference with such wave packets would set the stage for quantum-technology applications such as quantum information processing [1]. Various theoretical proposals [2][3][4][5][6][7] and experimental realizations [8][9][10][11][12][13][14][15][16][17] employ quantum Hall edge states [18] as electron waveguides. The group velocity and dispersion relation of edge states are important parameters for understanding and controlling electron wave packet propagation. For edge magnetoplasmons, the velocity can be deduced by time-of-flight measurements with gate pulses [19][20][21][22]. Such direct velocity measurements have been difficult with electron wave packets because gate pulses would also affect the background Fermi sea. Previous experiments [14,23,24] use other types of electron-transport data to estimate the electron velocity. Furthermore, electronelectron interactions can cause the formation of multiple collective modes traveling at different velocities, leading to decoherence [14,17,25]. In order to perform the measurements of bare group velocity by time-resolved methods, we need a robust edge-state waveguide system where the interactions between the transmitted electrons and other electrons in the background can be suppressed.In this Letter, we demonstrate an experimental method for probing the bare edge-state velocity of electrons traveling in a depleted edge of a two-dimensional system. Electrons are emitted from a tunable-barrier single-electron pump [26][27][28] approximately 100 meV above the Fermi energy [13,29]. These electrons are injected into an edge where the background two-dimensional electron gas (2DEG) is depleted to avoid the influence of electron-electron interactions. The arrival time of these wave packets is detected by an energyselective detector barrier with a picosecond resolution [13,16]. The travel length between the source and detector is switched by a deflection barrier. The time of flight of the extra path is measured as a delay in the arrival time at the detector [30]. The edge-state velocity is calculated from the length of the extra path and the time of flight. We find that the edge-state velocity is inversely propor...

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“…Coincidence correlation measurements allow the reconstruction of the full counting statistics, revealing regimes of statistically independent, distinguishable or correlated partitioning, and have been envisioned as a source of information on the quantum state of the electron pair [22][23][24][25][26] . The high pair-splitting fidelity opens a path to future on-demand generation of spin-entangled electron pairs from a suitably prepared two-electron quantum-dot ground state.The few-electron source is based on a single-parameter non-adiabatic quantized charge pump [27][28][29] , which enables the deterministic generation of single electrons and electron pairs with tunable emission energy 12,30 . Non-equilibrium electrons propagate along the edge of a quantum Hall sample with minimal inelastic scattering.…”

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confidence: 99%

Partitioning of on-demand electron pairs

et al. 2014

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The on-demand generation and separation of entangled photon pairs are key components of quantum information processing in quantum optics [1][2][3] . In an electronic analogue, the decomposition of electron pairs represents an essential building block for using the quantum state of ballistic electrons in electron quantum optics [4][5][6][7] . The scattering of electrons has been used to probe the particle statistics of stochastic sources in Hanbury Brown and Twiss experiments 8,9 and the recent advent of on-demand sources further offers the possibility to achieve indistinguishability between multiple sources in Hong-Ou-Mandel experiments [10][11][12][13][14][15] . Cooper pairs impinging stochastically at a mesoscopic beamsplitter have been successfully partitioned, as verified by measuring the coincidence of arrival [16][17][18][19][20][21] . Here, we demonstrate the splitting of electron pairs generated on demand. Coincidence correlation measurements allow the reconstruction of the full counting statistics, revealing regimes of statistically independent, distinguishable or correlated partitioning, and have been envisioned as a source of information on the quantum state of the electron pair [22][23][24][25][26] . The high pair-splitting fidelity opens a path to future on-demand generation of spin-entangled electron pairs from a suitably prepared two-electron quantum-dot ground state.The few-electron source is based on a single-parameter non-adiabatic quantized charge pump [27][28][29] , which enables the deterministic generation of single electrons and electron pairs with tunable emission energy 12,30 . Non-equilibrium electrons propagate along the edge of a quantum Hall sample with minimal inelastic scattering. The device and measurement set-up are presented in Fig. 1. An energy-selective detector barrier splits the incoming beam of electrons into two detector paths. The coincidence of arrival of electrons in the two detector channels leads to positive correlation between the time-dependent current signals. These correlations are inferred from a measurement of the zero-frequency cross-correlation shot noise. Although an oscillator-controlled electron source is noiseless 31 , the splitting of electron pairs generates partitioning noise and enables tomography of the probability distribution for the partitioning outcomes within each emission cycle.The generation and energy-selective detection of on-demand non-equilibrium electrons was demonstrated with the electron source configured to emit one electron with charge e and repetition frequency f of 280 MHz. Figure 2 shows the transmitted current I T as a function of barrier energy. The maximum level of I T is 2% below the emission current I P = 1 ef due to residual inelastic scattering events on the 2-µm-long path to the barrier (the emission error of the source is <1 × 10 −4). For energies greater than 57 meV, the current is pinched off as all of the emitted electrons are reflected at the beamsplitter. The emission energy is defined by the exit barrier height and ca...

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Generation of energy selective excitations in quantum Hall edge states

Cited by 66 publications

References 29 publications

Quantum Fluctuations and Coherence in High-Precision Single-Electron Capture

Quantum Fluctuations and Coherence in High-Precision Single-Electron Capture

Time-of-Flight Measurements of Single-Electron Wave Packets in Quantum Hall Edge States

Partitioning of on-demand electron pairs

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