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Excitons bound by photon exchange

Excitons bound by photon exchange
Excitons bound by photon exchange
In contrast to interband excitons in undoped quantum wells, doped quantum wells do not display sharp resonances due to excitonic bound states. In these systems the effective Coulomb interaction between electrons and holes typically only leads to a depolarization shift of the single electron intersubband transitions.
Nonperturbative light-matter interaction in solid-state devices has been investigated as a pathway to tune optoelectronic properties of materials. A recent theoretical work predicted that, when the doped quantum wells are embedded in a photonic cavity, emission-reabsorption processes of cavity photons can generate an effective attractive interaction which binds electrons and holes together, leading to the creation of an intraband bound exciton. Here we spectroscopically observe such a bound state as a discrete resonance which appears below the ionisation threshold only when the coupling between light and matter is increased above a critical value. Our result demonstrates that two charged particles can be bound by the exchange of transverse photons. Light-matter coupling can thus be used as a novel tool in quantum material engineering, tuning electronic properties of semiconductor heterostructures beyond those permitted by mere crystal structures, with direct applications to mid-infrared optoelectronics.
bound excitons, condensed matter, microcavity, two-dimensional electron gas
1745-2473
1-7
Cortese, Erika
1dd08835-71b4-4d4e-89ef-664f189718a2
Tran, Ngoc Linh
1c7f9b5c-4fe9-42d8-8bc9-db661392ea02
Manceau, Jean-Michel
9c978e15-d93b-43f5-99a1-9a4e847b9346
Bousseksou, Adel
4032340a-4a9c-407c-a11a-dc822fc86ed2
Carusotto, Iacopo
0cdf3ce4-0ec3-4721-9de6-9c4d723ad819
Biasol, Giorgio
032aed32-357c-42e3-ab36-5cedd3585fda
Colombelli, Raffaele
2eccb191-670d-4ce0-b22b-23e699dd195a
De Liberato, Simone
5942e45f-3115-4027-8653-a82667ed8473
Cortese, Erika
1dd08835-71b4-4d4e-89ef-664f189718a2
Tran, Ngoc Linh
1c7f9b5c-4fe9-42d8-8bc9-db661392ea02
Manceau, Jean-Michel
9c978e15-d93b-43f5-99a1-9a4e847b9346
Bousseksou, Adel
4032340a-4a9c-407c-a11a-dc822fc86ed2
Carusotto, Iacopo
0cdf3ce4-0ec3-4721-9de6-9c4d723ad819
Biasol, Giorgio
032aed32-357c-42e3-ab36-5cedd3585fda
Colombelli, Raffaele
2eccb191-670d-4ce0-b22b-23e699dd195a
De Liberato, Simone
5942e45f-3115-4027-8653-a82667ed8473

Cortese, Erika, Tran, Ngoc Linh, Manceau, Jean-Michel, Bousseksou, Adel, Carusotto, Iacopo, Biasol, Giorgio, Colombelli, Raffaele and De Liberato, Simone (2020) Excitons bound by photon exchange. Nature Physics, 1-7. (doi:10.1038/s41567-020-0994-6).

Record type: Letter

Abstract

In contrast to interband excitons in undoped quantum wells, doped quantum wells do not display sharp resonances due to excitonic bound states. In these systems the effective Coulomb interaction between electrons and holes typically only leads to a depolarization shift of the single electron intersubband transitions.
Nonperturbative light-matter interaction in solid-state devices has been investigated as a pathway to tune optoelectronic properties of materials. A recent theoretical work predicted that, when the doped quantum wells are embedded in a photonic cavity, emission-reabsorption processes of cavity photons can generate an effective attractive interaction which binds electrons and holes together, leading to the creation of an intraband bound exciton. Here we spectroscopically observe such a bound state as a discrete resonance which appears below the ionisation threshold only when the coupling between light and matter is increased above a critical value. Our result demonstrates that two charged particles can be bound by the exchange of transverse photons. Light-matter coupling can thus be used as a novel tool in quantum material engineering, tuning electronic properties of semiconductor heterostructures beyond those permitted by mere crystal structures, with direct applications to mid-infrared optoelectronics.

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Accepted/In Press date: 3 July 2020
e-pub ahead of print date: 17 August 2020
Keywords: bound excitons, condensed matter, microcavity, two-dimensional electron gas

Identifiers

Local EPrints ID: 444829
URI: http://eprints.soton.ac.uk/id/eprint/444829
ISSN: 1745-2473
PURE UUID: 32121a91-64e6-4753-9278-805aa685a220
ORCID for Simone De Liberato: ORCID iD orcid.org/0000-0002-4851-2633

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Date deposited: 06 Nov 2020 17:30
Last modified: 18 Feb 2021 17:21

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