Conditional Dynamics of Interacting Quantum Dots
Abstract
Conditional quantum dynamics, where the quantum state of one system controls the outcome of measurements on another quantum system, is at the heart of quantum information processing. We demonstrate conditional dynamics for two coupled quantum dots, whereby the probability that one quantum dot makes a transition to an optically excited state is controlled by the presence or absence of an optical excitation in the neighboring dot. Interaction between the dots is mediated by the tunnel coupling between optically excited states and can be optically gated by applying a laser field of the right frequency. Our results represent substantial progress toward realization of an optically effected controlled–phase gate between two solid-state qubits.
Get full access to this article
View all available purchase options and get full access to this article.
Already a Subscriber?Sign In
Supplementary Material
File (robledo.som.pdf)
References and Notes
1
P. M. Petroff, A. Lorke, A. Imamoglu, Phys. Today54, 46 (2001).
2
X. Liet al., Science301, 809 (2003).
3
M. O. Scully, M. S. Zubairy, Quantum Optics (Cambridge Univ. Press, Cambridge, 1997).
4
R. Hanson, L. P. Kouwenhoven, J. R. Petta, S. Tarucha, L. M. K. Vandersypen, Rev. Mod. Phys.79, 1217 (2007).
5
M. Atatüreet al., Science312, 551 (2006); published online 5April 2006 (
6
J. Berezovskyet al., Science314, 1916 (2006); published online 9November 2006 (
7
M. Atatüre, J. Dreiser, A. Badolato, A. Imamoglu, Nat. Phys.3, 101 (2007).
8
M. Kroneret al., preprint available at http://arxiv.org/abs/0710.4901.
9
M. H. Mikkelsen, J. Berezovsky, N. G. Stoltz, L. A. Coldren, D. D. Awschalom, Nat. Phys.3, 770 (2007).
10
D. Loss, D. P. DiVincenzo, Phys. Rev. A57, 120 (1998).
11
J. R. Pettaet al., Science309, 2180 (2005); published online 1September 2005 (
12
H. J. Krenneret al., Phys. Rev. Lett.94, 057402 (2005).
13
E. A. Stinaffet al., Science311, 636 (2006); published online 11January 2006 (
14
S. Fältet al., Phys. Rev. Lett.100, 106401 (2008).
15
T. Calarco, A. Datta, P. Fedichev, E. Pazy, P. Zoller, Phys. Rev. A68, 012310 (2003).
16
C. Hettichet al., Science298, 385 (2002); published online 5September 2002 (
17
T. Unold, K. Mueller, C. Lienau, T. Elsaesser, A. D. Wieck, Phys. Rev. Lett.94, 137404 (2005).
18
M. Bayeret al., Phys. Rev. B65, 195315 (2002).
19
D. Gammon, E. S. Snow, B. V. Shanabrook, D. S. Katzer, D. Park, Phys. Rev. Lett.76, 3005 (1996).
20
In principle, states |1〉 or |5〉 or |6〉 and |7〉 could be split because of electron tunneling, but each of these resonances will only occur at substantially different gate voltages because of the fact that the tunneling strength is much smaller than the relevant Coulomb interaction energies.
21
R. J. Warburtonet al., Nature405, 926 (2000).
22
In the inset, the mixing of the bright \( \(\mathrm{X}_{r}^{0}\) \) with the indirect exciton is hardly resolved. Clearly visible is the anticrossing of the indirect exciton with the dark \( \(\mathrm{X}_{r}^{0}\) \), which becomes bright because of the mixing (14).
23
B. Alén, F. Bickel, K. Karrai, R. J. Warburton, P. M. Petroff, Appl. Phys. Lett.83, 2235 (2003).
24
The gate voltage scale for the absorption measurements is slightly different from that of PL because of technical reasons (28).
25
To illustrate the observed effect clearly, the intensity of the probe laser is chosen such that it saturates the corresponding ground state transition, whereas the pump laser is set to five times the saturation intensity.
26
In addition to the strong shifted red absorption that occurs for a resonant blue laser (around 1334.63 meV), we also see a weak red absorption around 1261.04 meV even when the blue laser is not resonant. This effect, which is not present when the blue laser is turned off, indicates that even a nonresonant blue laser has a small probability to lift the tunneling resonance between states |2〉, |3〉, and |4〉. This is most likely due to the creation of charges in nearby impurity sites, which can shift the effective gate voltage felt by the CQD. Also, a faint diagonal absorption line is visible around the shifted resonance, which is due to two-photon resonance between states |1〉 and |6〉.
27
We have assumed that all excited states are lifetime-broadened.
28
Materials and methods are available on Science Online.
29
This work is supported by National Centre of Competence in Research Quantum Photonics (NCCR QP), research instrument of the Swiss National Science Foundation (SNSF), and European Union Research Training Network Engineering, Manipulation, and Characterization of Quantum States of Matter and Light (EMALI). The authors thank K. Weiss for experimental assistance.
Information & Authors
Information
Published In
Science
Volume 320 | Issue 5877
9 May 2008
9 May 2008
Copyright
American Association for the Advancement of Science.
Submission history
Received: 18 January 2008
Accepted: 1 April 2008
Published in print: 9 May 2008
Authors
Metrics & Citations
Metrics
Article Usage
Altmetrics
Citations
Export citation
Select the format you want to export the citation of this publication.
View Options
Get Access
Log in to view the full text
AAAS login provides access to Science for AAAS Members, and access to other journals in the Science family to users who have purchased individual subscriptions.
- Become a AAAS Member
- Activate your AAAS ID
- Purchase Access to Other Journals in the Science Family
- Account Help
Log in via OpenAthens.
Log in via Shibboleth.
More options
Purchase digital access to this article
Download and print this article for your personal scholarly, research, and educational use.
Buy a single issue of Science for just $15 USD.
View options
PDF format
Download this article as a PDF file
Download PDF