Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Physical Review B

Dark excitons in Cu2O crystals for two-photon coherence storage in semiconductors

Kosuke Yoshioka, Makoto Kuwata‐Gonokami

Published Feb 22, 2006• 23 citations
Publisher

Abstract

The two-photon coherence of infrared pulses is preserved for more than $250\phantom{\rule{0.3em}{0ex}}\mathrm{ps}$ by dark excitons in ${\mathrm{Cu}}_{2}\mathrm{O}$ crystals. Taking into account the nonlocal electron-hole exchange interaction, $1s$ orthoexcitons are split into one bright exciton state that is quadrupole active and two dark exciton states that are two-photon active but one-photon inactive. Interference of cold dark exciton waves excited by a phase-locked pulse pair is observed with an almost perfect visibility and a beating pattern indicating and an energy splitting in the $\ensuremath{\mu}\mathrm{eV}$ range is seen. The long-lived two-photon coherence of dark excitons indicates their strong potential for coherence storage applications.

DOI
10.1103/physrevb.73.081202

Related papers

Two‐photon coherent control of dark orthoexcitons in Cu2O

Kosuke Yoshioka, Makoto Kuwata‐Gonokami

Abstract We investigate experimentally the two‐photon coherence exhibited by optically forbidden exciton states in the bulk semiconductor Cu2O. Two‐photon coherent control is achieved by using phase‐locked optical pulse pairs. Very long dephasing times and a fine energy splittings of the order of µ‐eV are observed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Physica status solidi. C, Conferences and critical reviews/Physica status solidi. C, Current topics in solid state physics•Jul 5, 2006•0 citations

Quantum coherence of 1s orthoexcitons in Cu2O driven by resonant two-photon excitation

Shunsuke Kono, N. Nagasawa

The intensity of the resonant emission of the $1s$ orthoexcitons in ${\mathrm{Cu}}_{2}\mathrm{O}$ is observed in a weak magnetic field under two-photon resonant excitation at $1.6\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ to investigate the quantum interference within the Zeeman sublevels in the Faraday configuration. A specific decrease of $\ensuremath{\sim}15%$ in the emission intensity is observed in the region of $\ifmmode\pm\else\textpm\fi{}0.2\phantom{\rule{0.3em}{0ex}}\mathrm{T}$. This structure is interpreted as a manifestation of the quantum interference effect between the Zeeman sublevels of the $1s$ orthoexcitons, known as the Hanle effect in atomic spectroscopy. The homogeneous width of the exciton level is estimated to be $5.5\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{eV}$. The contribution of the quadrupole exciton polariton is discussed by taking into account the geometry-dependent characteristics of the exciton-polariton on the direction of the magnetic field. The Hanle structure observed is attributed to the interference of the polariton wave packets of the longitudinal excitons, where the phase coherence is transferred via transverse excitons driven by resonant two-photon coupling with the radiation field.

Physical Review B•Dec 22, 2006•1 citation

Coherent control of resonant two-photon excitation of cold excitons by phase modulated pulses

Makoto Kuwata‐Gonokami

By two-photon excitation with phase manipulated short laser pulses, we selectively generate ultracold excitons in Cu2O crystal while quenching a multiphoton excitation process of hot electrons and holes.

Conference on Lasers and Electro-Optics•Aug 30, 2009•0 citations

Emission quantum coherence and interference of excitons in cuprous oxide

Qianni Zhou, Yunke Zhou, Xiang Long +2 more

Emission coherence is crucial for quantum photonic technologies like single-photon emitters. However, emission from most bulk semiconductors suffers from severely limited coherence times under non-resonant excitation, typically in the femtosecond to picosecond range. In this study, we investigate the temporal coherence properties of excitons in cuprous oxide (Cu2O) using interferometric Fourier spectroscopy. We reveal a coherence time of approximately 24 ps and a homogeneous linewidth of 0.017 nm (55 μeV) at 4.7 K under non-resonant two-photon excitation. We also analyze the impact of relaxation, scattering, and the experimental setup on the decrease in coherence time. The 1S orthoexciton shows robust photoluminescence intensity and negligible spectral diffusion over 120 min. These results suggest that Cu2O presents itself as an exceptional material for generating indistinguishable single photons, demonstrating considerable potential for advanced applications in quantum photonics.

Applied Physics Letters•Sep 1, 2025•1 citation

Experiments on excitons in bulk semiconductors

Makoto Kuwata‐Gonokami

Abstract This chapter begins with a discussion of excitonic matter in semiconductors. It then describes experimental methods for generating highly degenerate excitonic particles by using energy- and momentum-selective optical excitation processes for biexcitons in CuCl and orthoexcitons in Cu2O. Phase-sensitive interference of particles demonstrates the macroscopic coherence of such ensembles of cold particles prepared in the quantum degenerate regime. This is followed by a discussion of the search for spontaneous Bose–Einstein condensation of excitons in a bulk crystal of Cu2O.

Oxford University Press eBooks•Feb 28, 2013•0 citations

Optical coherence storage in dark exciton states using spin-dependent three-pulse photon echo

I. A. Solovev, Roman S. Nazarov, A. A. Butiugina +5 more

Extension of coherence time is a desired goal in the field of all-optical information processing implemented in both classical and quantum ways. Here we show how the decay time of a coherent signal from localized excitons can be significantly increased utilizing the spin degree of freedom. To experimentally demonstrate this effect, we studied three-pulse photon echoes from excitons in a single InGaAs/GaAs quantum well subject to a transverse magnetic field. Field-induced quantum beats lead to oscillation of the exciton population between short-lived bright and long-lived dark states during the coherence storage period between the second and third excitation pulses. In the aperiodic regime, the echo signal decay time tends to the dark exciton lifetime, which leads to an increase in the photon echo decay time by an order of magnitude.

arXiv:2312.03156•Physical review. B./Physical review. B•Jan 16, 2025•0 citations
The two-photon coherence of infrared pulses is preserved for more than 250ps250\phantom{\rule{0.3em}{0ex}}\mathrm{ps}250ps by dark excitons in Cu2O{\mathrm{Cu}}_{2}\mathrm{O}Cu2​O crystals. Taking into account the nonlocal electron-hole exchange interaction, 1s1s1s orthoexcitons are split into one bright exciton state that is quadrupole active and two dark exciton states that are two-photon active but one-photon inactive. Interference of cold dark exciton waves excited by a phase-locked pulse pair is observed with an almost perfect visibility and a beating pattern indicating and an energy splitting in the \ensuremathμeV\ensuremath{\mu}\mathrm{eV}\ensuremathμeV range is seen. The long-lived two-photon coherence of dark excitons indicates their strong potential for coherence storage applications.
The intensity of the resonant emission of the 1s1s1s orthoexcitons in Cu2O{\mathrm{Cu}}_{2}\mathrm{O}Cu2​O is observed in a weak magnetic field under two-photon resonant excitation at 1.6K1.6\phantom{\rule{0.3em}{0ex}}\mathrm{K}1.6K to investigate the quantum interference within the Zeeman sublevels in the Faraday configuration. A specific decrease of $\ensuremath{\sim}15%$ in the emission intensity is observed in the region of $\ifmmode\pm\else\textpm\fi{}0.2\phantom{\rule{0.3em}{0ex}}\mathrm{T}$. This structure is interpreted as a manifestation of the quantum interference effect between the Zeeman sublevels of the 1s1s1s orthoexcitons, known as the Hanle effect in atomic spectroscopy. The homogeneous width of the exciton level is estimated to be $5.5\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{eV}$. The contribution of the quadrupole exciton polariton is discussed by taking into account the geometry-dependent characteristics of the exciton-polariton on the direction of the magnetic field. The Hanle structure observed is attributed to the interference of the polariton wave packets of the longitudinal excitons, where the phase coherence is transferred via transverse excitons driven by resonant two-photon coupling with the radiation field.
Emission coherence is crucial for quantum photonic technologies like single-photon emitters. However, emission from most bulk semiconductors suffers from severely limited coherence times under non-resonant excitation, typically in the femtosecond to picosecond range. In this study, we investigate the temporal coherence properties of excitons in cuprous oxide (Cu2O) using interferometric Fourier spectroscopy. We reveal a coherence time of approximately 24 ps and a homogeneous linewidth of 0.017 nm (55 μeV) at 4.7 K under non-resonant two-photon excitation. We also analyze the impact of relaxation, scattering, and the experimental setup on the decrease in coherence time. The 1S orthoexciton shows robust photoluminescence intensity and negligible spectral diffusion over 120 min. These results suggest that Cu2O presents itself as an exceptional material for generating indistinguishable single photons, demonstrating considerable potential for advanced applications in quantum photonics.
Abstract This chapter begins with a discussion of excitonic matter in semiconductors. It then describes experimental methods for generating highly degenerate excitonic particles by using energy- and momentum-selective optical excitation processes for biexcitons in CuCl and orthoexcitons in Cu2O. Phase-sensitive interference of particles demonstrates the macroscopic coherence of such ensembles of cold particles prepared in the quantum degenerate regime. This is followed by a discussion of the search for spontaneous Bose–Einstein condensation of excitons in a bulk crystal of Cu2O.
Extension of coherence time is a desired goal in the field of all-optical information processing implemented in both classical and quantum ways. Here we show how the decay time of a coherent signal from localized excitons can be significantly increased utilizing the spin degree of freedom. To experimentally demonstrate this effect, we studied three-pulse photon echoes from excitons in a single InGaAs/GaAs quantum well subject to a transverse magnetic field. Field-induced quantum beats lead to oscillation of the exciton population between short-lived bright and long-lived dark states during the coherence storage period between the second and third excitation pulses. In the aperiodic regime, the echo signal decay time tends to the dark exciton lifetime, which leads to an increase in the photon echo decay time by an order of magnitude.