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

Journal of Modern Optics

Photon-echo technique for reducing the decoherence of a quantum bit

Masashi Ban

Published Nov 1, 1998• 122 citations
Publisher

Abstract

A useful method for reducing the decoherence of a quantum bit (qubit) is proposed, which is based on the photon-echo phenomenon in coherent optical transient. The decoherence of the qubit is caused by the dephasing coupling with a bosonic thermal reservoir. In the method, successive coherent π pulses are applied with very short pulse widths to reduce the decoherence. It is found that the decoherence of the qubit disappears at a certain time which can be controlled by appropriately choosing the pulse separation time and the number π pulses.

DOI
10.1080/09500349808231241

Related papers

Theory of multiwave mixing and decoherence control in a qubit array system

Masahide Sasaki, Atsushi Hasegawa, Junko Ishi‐Hayase +2 more

We develop a theory to analyze the decoherence effect in a charged qubit array system with photon-echo signals in the multiwave mixing configuration. We present how the decoherence-suppression effect by the bang-bang control with the $\ensuremath{\pi}$ pulses can be demonstrated in the laboratory by using a bulk ensemble of exciton qubits and optical pulses with a pulse area that is even smaller than $\ensuremath{\pi}$. Analysis is made on the time-integated multiwave mixing signals diffracted into certain phase-matching directions from a bulk ensemble. Depending on the pulse-interval conditions, the crossover from the decoherence-acceleration regime to the decoherence-suppression regime, which is a peculiar feature of the coherent interaction between a qubit and the reservoir bosons, may be observed in the time-integated multiwave mixing signals in the realistic case, including the inhomogeneous broadening effect. Our analysis will be successfully applied to the precise estimation of the reservoir parameters from the experimental data of the direction-resolved signal intensities obtained in the multiwave mixing technique.

arXiv:quant-ph/0411021•Physical Review B•Apr 18, 2005•16 citations

Pulse Control of Decoherence in a Qubit Coupled with a Quantum Environment

Takahiro Murakami, Yositake Takane

We study the time evolution of a qubit linearly coupled with a quantum environment under a sequence of short π pulses.Our attention is focused on the case where qubit-environment interactions induce the decoherence with population decay.We assume that the environment consists of a set of bosonic excitations.The time evolution of the reduced density matrix for the qubit is calculated in the presence of periodic short π pulses.We confirm that the decoherence is suppressed if the pulse interval is shorter than the correlation time for qubit-environment interactions.

arXiv:quant-ph/0411101•Journal of the Physical Society of Japan•Jan 1, 2005•1 citation

Pulse Control of Decoherence with Population Decay

Takahiro Murakami, Yositake Takane

The pulse control of decoherence in a qubit interacting with a quantum environment is studied with focus on a general case where decoherence is induced by both pure dephasing and population decay. To observe how the decoherence is suppressed by periodic pi pulses, we present a simple method to calculate the time evolution of a qubit under arbitrary pulse sequences consisting of bit-flips and/or phase-flips. We examine the effectiveness of the two typical sequences: bb sequence consisting of only bit-flips, and bp sequence consisting of both bit- and phase-flips. It is shown that the effectiveness of the pulse sequences depends on a relative strength of the two decoherence processes especially when a pulse interval is slightly shorter than qubit-environment correlation times. In the short-interval limit, however, the bp sequence is always more effective than, or at least as effective as, the bb sequence.

arXiv:quant-ph/0508080•Journal of the Physical Society of Japan•Feb 15, 2006•0 citations

Pulse Control of Dephasing in Two-Level Quantum Systems

Yositake Takane, Takahiro Murakami

The pulse control of dephasing is studied for a two-level quantum system (qubit) interacting with a quantum environment. It has been shown that dephasing in a qubit due to qubit–environment interactions can be suppressed by a sequence of periodic π pulses with infinitely short duration. To study how the effectiveness of the pulse control is affected by finite pulse duration t d , we calculate the time evolution of the reduced density operator for a qubit under a sequence of π pulses. We show that the pulse control is effective even for not short t d if a suitable pulse sequence is adopted.

Journal of the Physical Society of Japan•Aug 1, 2005•6 citations

Suppressing phase decoherence of a single atom qubit with Carr-Purcell-Meiboom-Gill sequence

Shi Yu, Peng Xu, Xiaodong He +3 more

We experimentally demonstrate the strong suppression of dephasing of a qubit stored in a single 87Rb atom in an optical dipole trap by using Carr-Purcell-Meiboom-Gill (CPMG) pulse sequences. Regarded as a repetition of spin echo, CPMG sequence is an excellent choice for suppressing both inhomogeneous and homogeneous phase decoherence mechanisms. In comparison with atomic ensembles, the dephasing due to atomic collisions disappears for individual atoms. Thus, CPMG suppression effect is efficient with a few π-pulses. In our trap with 830 nm wavelength and 0.7 mK potential depth, the reversible inhomogeneous dephasing time is T2*=1.4 ms. We obtain the homogeneous dephasing time of T'2 = 103 ms in the spin echo process. By employing CPMG sequence with pulse number n = 6, the homogeneous dephasing is further suppressed by a factor of 3, and its corresponding coherence time is extended to T'2 = 304 ms.

Optics Express•Dec 18, 2013•21 citations

Accurate photon echo timing by optical freezing of exciton dephasing and rephasing in quantum dots

Alexander N. Kosarev, Hendrik Rose, S. V. Poltavtsev +7 more

Abstract Semiconductor quantum dots are excellent candidates for ultrafast coherent manipulation of qubits by laser pulses on picosecond timescales or even faster. In inhomogeneous ensembles a macroscopic optical polarization decays rapidly due to dephasing, which, however, is reversible in photon echoes carrying complete information about the coherent ensemble dynamics. Control of the echo emission time is mandatory for applications. Here, we propose a concept to reach this goal. In a two-pulse photon echo sequence, we apply an additional resonant control pulse with multiple of 2πarea. Depending on its arrival time, the control slows down dephasing or rephasing of the exciton ensemble during its action. We demonstrate for self-assembled (In,Ga)As quantum dots that the photon echo emission time can be retarded or advanced by up to 5 ps relative to its nominal appearance time without control. This versatile protocol may be used to obtain significantly longer temporal shifts for suitably tailored control pulses.

Communications Physics•Dec 8, 2020•18 citations
A useful method for reducing the decoherence of a quantum bit (qubit) is proposed, which is based on the photon-echo phenomenon in coherent optical transient. The decoherence of the qubit is caused by the dephasing coupling with a bosonic thermal reservoir. In the method, successive coherent π pulses are applied with very short pulse widths to reduce the decoherence. It is found that the decoherence of the qubit disappears at a certain time which can be controlled by appropriately choosing the pulse separation time and the number π pulses.
We develop a theory to analyze the decoherence effect in a charged qubit array system with photon-echo signals in the multiwave mixing configuration. We present how the decoherence-suppression effect by the bang-bang control with the $\ensuremath{\pi}$ pulses can be demonstrated in the laboratory by using a bulk ensemble of exciton qubits and optical pulses with a pulse area that is even smaller than $\ensuremath{\pi}$. Analysis is made on the time-integated multiwave mixing signals diffracted into certain phase-matching directions from a bulk ensemble. Depending on the pulse-interval conditions, the crossover from the decoherence-acceleration regime to the decoherence-suppression regime, which is a peculiar feature of the coherent interaction between a qubit and the reservoir bosons, may be observed in the time-integated multiwave mixing signals in the realistic case, including the inhomogeneous broadening effect. Our analysis will be successfully applied to the precise estimation of the reservoir parameters from the experimental data of the direction-resolved signal intensities obtained in the multiwave mixing technique.
We study the time evolution of a qubit linearly coupled with a quantum environment under a sequence of short π pulses.Our attention is focused on the case where qubit-environment interactions induce the decoherence with population decay.We assume that the environment consists of a set of bosonic excitations.The time evolution of the reduced density matrix for the qubit is calculated in the presence of periodic short π pulses.We confirm that the decoherence is suppressed if the pulse interval is shorter than the correlation time for qubit-environment interactions.
The pulse control of decoherence in a qubit interacting with a quantum environment is studied with focus on a general case where decoherence is induced by both pure dephasing and population decay. To observe how the decoherence is suppressed by periodic pi pulses, we present a simple method to calculate the time evolution of a qubit under arbitrary pulse sequences consisting of bit-flips and/or phase-flips. We examine the effectiveness of the two typical sequences: bb sequence consisting of only bit-flips, and bp sequence consisting of both bit- and phase-flips. It is shown that the effectiveness of the pulse sequences depends on a relative strength of the two decoherence processes especially when a pulse interval is slightly shorter than qubit-environment correlation times. In the short-interval limit, however, the bp sequence is always more effective than, or at least as effective as, the bb sequence.
The pulse control of dephasing is studied for a two-level quantum system (qubit) interacting with a quantum environment. It has been shown that dephasing in a qubit due to qubit–environment interactions can be suppressed by a sequence of periodic π pulses with infinitely short duration. To study how the effectiveness of the pulse control is affected by finite pulse duration t d , we calculate the time evolution of the reduced density operator for a qubit under a sequence of π pulses. We show that the pulse control is effective even for not short t d if a suitable pulse sequence is adopted.
We experimentally demonstrate the strong suppression of dephasing of a qubit stored in a single 87Rb atom in an optical dipole trap by using Carr-Purcell-Meiboom-Gill (CPMG) pulse sequences. Regarded as a repetition of spin echo, CPMG sequence is an excellent choice for suppressing both inhomogeneous and homogeneous phase decoherence mechanisms. In comparison with atomic ensembles, the dephasing due to atomic collisions disappears for individual atoms. Thus, CPMG suppression effect is efficient with a few π-pulses. In our trap with 830 nm wavelength and 0.7 mK potential depth, the reversible inhomogeneous dephasing time is T2*=1.4 ms. We obtain the homogeneous dephasing time of T'2 = 103 ms in the spin echo process. By employing CPMG sequence with pulse number n = 6, the homogeneous dephasing is further suppressed by a factor of 3, and its corresponding coherence time is extended to T'2 = 304 ms.
Abstract Semiconductor quantum dots are excellent candidates for ultrafast coherent manipulation of qubits by laser pulses on picosecond timescales or even faster. In inhomogeneous ensembles a macroscopic optical polarization decays rapidly due to dephasing, which, however, is reversible in photon echoes carrying complete information about the coherent ensemble dynamics. Control of the echo emission time is mandatory for applications. Here, we propose a concept to reach this goal. In a two-pulse photon echo sequence, we apply an additional resonant control pulse with multiple of 2πarea. Depending on its arrival time, the control slows down dephasing or rephasing of the exciton ensemble during its action. We demonstrate for self-assembled (In,Ga)As quantum dots that the photon echo emission time can be retarded or advanced by up to 5 ps relative to its nominal appearance time without control. This versatile protocol may be used to obtain significantly longer temporal shifts for suitably tailored control pulses.