Electron counting in quantum dots
Document type :
Article dans une revue scientifique
Title :
Electron counting in quantum dots
Author(s) :
Gustavsson, S. [Auteur]
Leturcq, R. [Auteur]
Studer, M. [Auteur]
Shorubalko, I. [Auteur]
Ihn, T. [Auteur]
Ensslin, K. [Auteur]
Driscoll, D.C. [Auteur]
Gossard, A.C. [Auteur]
Leturcq, R. [Auteur]
Studer, M. [Auteur]
Shorubalko, I. [Auteur]
Ihn, T. [Auteur]
Ensslin, K. [Auteur]
Driscoll, D.C. [Auteur]
Gossard, A.C. [Auteur]
Journal title :
Surface Science Reports
Pages :
191-232
Publisher :
Elsevier
Publication date :
2009-05-28
ISSN :
0167-5729
English keyword(s) :
current fluctuations
Coulomb blockade
semiconductor quantum dots
gallium arsenide
III-V semiconductors
photon-electron interactions
quantum point contacts
Aharonov-Bohm effect
Coulomb blockade
semiconductor quantum dots
gallium arsenide
III-V semiconductors
photon-electron interactions
quantum point contacts
Aharonov-Bohm effect
HAL domain(s) :
Physique [physics]
English abstract : [en]
We use time-resolved charge detection techniques to investigate single-electron tunneling in semiconductor quantum dots. Theability to detect individual charges in real-time makes it possible to count electrons one-by-one ...
Show more >We use time-resolved charge detection techniques to investigate single-electron tunneling in semiconductor quantum dots. Theability to detect individual charges in real-time makes it possible to count electrons one-by-one as they pass through the structure.The setup can thus be used as a high-precision current meter for measuring ultra-low currents, with resolution several orders ofmagnitude better than that of conventional current meters. In addition to measuring the average current, the counting procedurealso makes it possible to investigate correlations between charge carriers. Electron correlations are conventionally probed in noisemeasurements, which are technically challenging due to the difficulty to exclude the influence of external noise sources in theexperimental setup. Using real-time charge detection techniques, we circumvent the problem by studying the electron correlationdirectly from the counting statistics of the tunneling electrons. In quantum dots, we find that the strong Coulomb interaction makeselectrons try to avoid each other. This leads to electron anti-bunching, giving stronger correlations and reduced noise compared toa current carried by statistically independent electrons.The charge detector is implemented by monitoring changes in conductance in a near-by capacitively coupled quantum pointcontact. We find that the quantum point contact not only serves as a detector but also causes a back-action onto the measureddevice. Electron scattering in the quantum point contact leads to emission of microwave radiation. The radiation is found toinduce an electronic transition between two quantum dots, similar to the absorption of light in real atoms and molecules. Usinga charge detector to probe the electron transitions, we can relate a single-electron tunneling event to the absorption of a singlephoton. Moreover, since the energy levels of the double quantum dot can be tuned by external gate voltages, we use the deviceas a frequency-selective single-photon detector operating at microwave energies. The ability to put an on-chip microwave detectorclose to a quantum conductor opens up the possibility to investigate radiation emitted from mesoscopic structures and give a deeperunderstanding of the role of electron-photon interactions in quantum conductors.A central concept of quantum mechanics is the wave-particle duality; matter exhibits both wave- and particle-like propertiesand can not be described by either formalism alone. To investigate the wave properties of the electrons, we perform experimentson a structure containing a double quantum dot embedded in the Aharonov-Bohm ring interferometer. Aharonov-Bohm rings aretraditionally used to study interference of electron waves traversing different arms of the ring, in a similar way to the double-slitsetup used for investigating interference of light waves. In our case, we use the time-resolved charge detection techniques to detectelectrons one-by-one as they pass through the interferometer. We find that the individual particles indeed self-interfere and giverise to a strong interference pattern as a function of external magnetic field. The high level of control in the system together withthe ability to detect single electrons enables us to make direct observations of non-intuitive fundamental quantum phenomena likesingle-particle interference or time-energy uncertainty relationsShow less >
Show more >We use time-resolved charge detection techniques to investigate single-electron tunneling in semiconductor quantum dots. Theability to detect individual charges in real-time makes it possible to count electrons one-by-one as they pass through the structure.The setup can thus be used as a high-precision current meter for measuring ultra-low currents, with resolution several orders ofmagnitude better than that of conventional current meters. In addition to measuring the average current, the counting procedurealso makes it possible to investigate correlations between charge carriers. Electron correlations are conventionally probed in noisemeasurements, which are technically challenging due to the difficulty to exclude the influence of external noise sources in theexperimental setup. Using real-time charge detection techniques, we circumvent the problem by studying the electron correlationdirectly from the counting statistics of the tunneling electrons. In quantum dots, we find that the strong Coulomb interaction makeselectrons try to avoid each other. This leads to electron anti-bunching, giving stronger correlations and reduced noise compared toa current carried by statistically independent electrons.The charge detector is implemented by monitoring changes in conductance in a near-by capacitively coupled quantum pointcontact. We find that the quantum point contact not only serves as a detector but also causes a back-action onto the measureddevice. Electron scattering in the quantum point contact leads to emission of microwave radiation. The radiation is found toinduce an electronic transition between two quantum dots, similar to the absorption of light in real atoms and molecules. Usinga charge detector to probe the electron transitions, we can relate a single-electron tunneling event to the absorption of a singlephoton. Moreover, since the energy levels of the double quantum dot can be tuned by external gate voltages, we use the deviceas a frequency-selective single-photon detector operating at microwave energies. The ability to put an on-chip microwave detectorclose to a quantum conductor opens up the possibility to investigate radiation emitted from mesoscopic structures and give a deeperunderstanding of the role of electron-photon interactions in quantum conductors.A central concept of quantum mechanics is the wave-particle duality; matter exhibits both wave- and particle-like propertiesand can not be described by either formalism alone. To investigate the wave properties of the electrons, we perform experimentson a structure containing a double quantum dot embedded in the Aharonov-Bohm ring interferometer. Aharonov-Bohm rings aretraditionally used to study interference of electron waves traversing different arms of the ring, in a similar way to the double-slitsetup used for investigating interference of light waves. In our case, we use the time-resolved charge detection techniques to detectelectrons one-by-one as they pass through the interferometer. We find that the individual particles indeed self-interfere and giverise to a strong interference pattern as a function of external magnetic field. The high level of control in the system together withthe ability to detect single electrons enables us to make direct observations of non-intuitive fundamental quantum phenomena likesingle-particle interference or time-energy uncertainty relationsShow less >
Language :
Anglais
Peer reviewed article :
Oui
Audience :
Non spécifiée
Popular science :
Non
Source :
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