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Tuesday, August 12 • 14:30 - 16:30
Quantum Optics, Nanophotonics IV

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14:30-14:45
Oral: Gustavo D. Cipagauta
Detuning-Control of Exciton Entanglement in Two Quantum Dots Coupled to a Photonic Mode
Co-authors: Karen M. Fonseca-Romero

14:45-15:00
Oral: Amir Capua
Direct Observation of Wavefunction Decoherence & Control over the Electronic Quantum State in a Room-Temperature InAs/InP Quantum Dot Semiconductor Optical Amplifier
Co-authors: Ouri Karni, Gadi Eisenstein, Vitalii Ivanov, Vitalii Sichkovskyi, Johann Peter Reithmaier

15:00-15:30
Invited: Jonathan H. Prechtel
Coherent Population Trapping on a Single Hole Spin in a Semiconductor Quantum Dot
Co-authors: Andreas V. Kuhlmann, Julien Houel, Arne Ludwig, Andreas D. Wieck, Richard J. Warburton

The coherence of an electron spin qubit in a semiconductor quantum dot (QD) is limited by the hyperfine interaction with the nuclear spins. Switching to a hole spin may bypass this problem. The hyperfine interaction of a pure heavy hole spin has a dipole-dipole term along the growth direction only such that the coupling to the nuclear spins is highly suppressed in an in-plane magnetic field [1]. We explore here the extent to which this ideal limit can be achieved in practice using coherent population trapping (CPT), a quantum interference which arises between two ground states, here the hole spin states, and a common upper level, here the exciton state of an InGaAs quantum dot. CPT enables a precise spectroscopic measurement of the hole Zeeman splitting ZH and also a probe of hole spin decoherence. The long hole spin coherence enables us to achieve CPT dips of just 33 neV (8 MHz) width.

We find that ZH depends on vertical electric field, F. While ZH is QD-dependent, dZH/dF is largely the same for all QDs in our sample. We show that via this mechanism, charge noise results in significant hole spin dephasing in our good but imperfect device. The interaction with the nuclear spins is quantified by polarizing the nuclear spins optically, measuring ZH with CPT. In an in-plane magnetic field of 3 T, ZH remains the same (to within our error of 20 neV) even as the electron Zeeman energy changes by 12 eV. This demonstrates a remarkably effective decoupling of the hole spin from the nuclear spins.

[1] J. Fischer et al, Phys. Rev. B 78, 155329 (2008).

15:30-15:45
Oral: Carlos Anton
Momentum Space Interferences as an Evidence of Remote Quantum Coherence of Condensates
Co-authors: Guilherme Tosi, Maria Dolores Martin, Zacharias Hatzopoulos, Georgios Konstantinidis, Peter Eldridge, Pavlos Savvidis, Carlos Tejedor, Luis Viña

15:45-16:00
Oral: Yves Leandre Delley
Coherent Spin Qubits in Optically Active InGaAs Quantum Dots
Co-authors: Wei-bo Gao, Aymeric Delteil, Priska Studer, Martin Kroner, Stefan Fält, Werner Wegscheider, Ataç İmamoğlu

16:00-16:15
Oral: John Bradley
Nano-Epitaxy as a Platform for Quantum Photonics
Co-authors: Andrew Foster, Andrey Krysa, Ben Royall, Paul Fry, Maurice Skolnick, Luke Wilson

16:15-16:30
Oral: Clemens Matthiesen
Measuring the Local Environment of a Quantum Dot
Co-authors: Megan Stanley, Jack Hansom, Claire Le Gall, Mete Atature

Session Chairs
GF

Greg Fuchs

Assistant Professor & Rebecca Q. & James C. Morgan Sesquicentennial Faculty Fellow, Cornell University
Fuchs earned his Ph.D. from Cornell University in 2007. Afterward, he moved to the University of California, Santa Barbara as a postdoctoral associate. In 2011, he joined the Cornell faculty of Applied and Engineering Physics. In 2012 he received a Young Investigator Award from the Air Force Office of Scientific Research, and in 2013 he received an Early Faculty Career Award from the National Science Foundation and the Presidential Early Career... Read More →

Speakers
JH

Jonathan H. Prechtel

University of Basel


Tuesday August 12, 2014 14:30 - 16:30
Room 18AB

Attendees (23)