Controlled Dephasing of a Quantum Dot: From Coherent to Sequential Tunneling

Rohrlich, Daniel; Zarchin, O.; Heiblum, Moty; Mahalu, D.; Umansky, V.

doi:10.1103/physrevlett.98.096803

Cited by 19 publications

(13 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In previous which path experiments using quantum conductors, the dephasing occurred by coupling the electrons to a noisy electromagnetic environment [5,8,9,10]. In our set-up, electrons re-emitted into the interferometer cannot be distinguished from the other electrons of the probe.…”

mentioning

confidence: 94%

“…Equation 2 is thus a consequence of the floating contact not affecting the mean current: all the charges that have been absorbed into it are re-injected into the circuit, so that the sum of the measured transmitted current I T and of the current absorbed by the upper small ohmic contact I R is conserved. In previous which path experiments using quantum conductors, the dephasing occurred by coupling the electrons to a noisy electromagnetic environment [5,8,9,10]. In our set-up, electrons re-emitted into the interferometer cannot be distinguished from the other electrons of the probe.…”

mentioning

confidence: 94%

See 1 more Smart Citation

Tuning Decoherence with a Voltage Probe

et al. 2009

View full text Add to dashboard Cite

We present an experiment where we tune the decoherence in a quantum interferometer using one of the simplest objects available in the physics of quantum conductors: an Ohmic contact. For that purpose, we designed an electronic Mach-Zehnder interferometer which has one of its two arms connected to an Ohmic contact through a quantum point contact. At low temperature, we observe quantum interference patterns with a visibility up to 57%. Increasing the connection between one arm of the interferometer to the floating Ohmic contact, the voltage probe, reduces quantum interference as it probes the electron trajectory. This unique experimental realization of a voltage probe works as a trivial which-path detector whose efficiency can be simply tuned by a gate voltage.

show abstract

mentioning

confidence: 94%

mentioning

confidence: 94%

Tuning Decoherence with a Voltage Probe

et al. 2009

View full text Add to dashboard Cite

show abstract

“…The influence of a gate coupled to one arm of the interferometer can be modelled in two equivalent ways. One can either consider that a gate voltage changes the surface S of the MZI without modifying the potential U 1 felt by the electrons, or that it adds an excess charge [4,10,13] …”

mentioning

confidence: 99%

Noise Dephasing in Edge States of the Integer Quantum Hall Regime

et al. 2008

View full text Add to dashboard Cite

An electronic Mach Zehnder interferometer is used in the integer quantum hall regime at filling factor 2, to study the dephasing of the interferences. This is found to be induced by the electrical noise existing in the edge states capacitively coupled to each others. Electrical shot noise created in one channel leads to phase randomization in the other, which destroys the interference pattern. These findings are extended to the dephasing induced by thermal noise instead of shot noise: it explains the underlying mechanism responsible for the finite temperature coherence time τϕ(T ) of the edge states at filling factor 2, measured in a recent experiment. Finally, we present here a theory of the dephasing based on Gaussian noise, which is found in excellent agreement with our experimental results.Although many experiments in quantum optics can be reproduced with electron beams using the edge states of the Integer Quantum Hall Effect (IQHE), there exist fundamental differences due to the Coulomb interaction. As an example, the Mach-Zenhder type of interferometer in the IQHE [1] has recently allowed to observe quantum interferences with the unprecedented 90% visibility [2], opening a new field of promising quantum information experiments. Indeed, the edge states of the IQHE provide a way to obtain 'ideal' uni-dimensional quantum wires. However, very little is known about the decoherence processes in these 'ideal' wires. Only very recently their coherence length was quantitatively determined as well as its temperature dependence established [3]. Here, we show that the underlying mechanism responsible for the finite coherence length is the thermal noise combined with the poor screening in the IQHE regime [4].In the IQHE, gapless excitations develop on the edge of the sample and form one dimensional chiral wires (edge states), the number of which is determined by the number of electrons per quantum of flux (the filling factor ν). In these wires, the electrons drift along the edge in a beam-like motion making experiments usually done with photons possible with electrons. The choice of the filling factor at which one obtains high visibility interferences requires a compromise between a magnetic field high enough to form well defined edge states, and small enough to still deal with a good Fermi liquid. Naïvely one could think that the highest visibility would have been observed at ν = 1, but it is not actually the case[1]. This is most probably due to decoherence induced by low energy collective spin excitations (skyrmions [5]) making spin flip processes possible. In practice, the highest visibility (90% [2]) has been obtained at filling factor 2, when there are two spin polarized edge states. Here, chirality and uni-dimensionality prevent first order inelastic scattering in the wires themselves [6], while tunneling from one edge to the other requires spin flip [7].To show that the origin of the finite coherence length is related to the coupling between two neighbouring edge states, we have proceeded as follow. First we ha...

show abstract

“…As recently reported, a single vibrational mode of a QD array enhances the electron transport and partially preserves its phase information [95]. The coherent transport of electrons in QDs is also sensitive to spin flip, electron-electron interaction, and external detectors [96][97][98][99][100][101][102][103][104]. A cantilever-based which-path charge detector has been previously studied [105,106]; this detector is based on dot-cantilever coupling, which causes remarkable dephasing to electrons.…”

Section: Introductionmentioning

confidence: 99%

Single molecular shuttle-junction: Shot noise and decoherence

Lai

Zhang

2015

Front. Phys.

View full text Add to dashboard Cite

Single molecular shuttle-junction is one kind of nanoscale electromechanical tunneling system. In this junction, a molecular island oscillates depending on its charge occupation, and this charge dependent oscillation leads to modulation of electron tunneling through the molecular island. This paper reviews recent development on the study of current, shot noise and decoherence of electrons in the single molecular shuttle-junction. We will give detailed discussion on this topic using the typical system model, the theory of fully quantum master equation and the Aharonov-Bohm interferometer.

show abstract

Controlled Dephasing of a Quantum Dot: From Coherent to Sequential Tunneling

Cited by 19 publications

References 19 publications

Tuning Decoherence with a Voltage Probe

Tuning Decoherence with a Voltage Probe

Noise Dephasing in Edge States of the Integer Quantum Hall Regime

Single molecular shuttle-junction: Shot noise and decoherence

Contact Info

Product

Resources

About