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Paul J, Stevens CE, Smith RP, Dey P, Mapara V, Semenov D, McGill SA, Kaindl RA, Hilton DJ, Karaiskaj D. Coherent two-dimensional Fourier transform spectroscopy using a 25 Tesla resistive magnet. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:063901. [PMID: 31255018 DOI: 10.1063/1.5055891] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 05/12/2019] [Indexed: 06/09/2023]
Abstract
We performed nonlinear optical two-dimensional Fourier transform spectroscopy measurements using an optical resistive high-field magnet on GaAs quantum wells. Magnetic fields up to 25 T can be achieved using the split helix resistive magnet. Two-dimensional spectroscopy measurements based on the coherent four-wave mixing signal require phase stability. Therefore, these measurements are difficult to perform in environments prone to mechanical vibrations. Large resistive magnets use extensive quantities of cooling water, which causes mechanical vibrations, making two-dimensional Fourier transform spectroscopy very challenging. Here, we report on the strategies we used to overcome these challenges and maintain the required phase-stability throughout the measurement. A self-contained portable platform was used to set up the experiments within the time frame provided by a user facility. Furthermore, this platform was floated above the optical table in order to isolate it from vibrations originating from the resistive magnet. Finally, we present two-dimensional Fourier transform spectra obtained from GaAs quantum wells at magnetic fields up to 25 T and demonstrate the utility of this technique in providing important details, which are obscured in one dimensional spectroscopy.
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Affiliation(s)
- Jagannath Paul
- Department of Physics, University of South Florida, Tampa, Florida 33620, USA
| | | | - Ryan P Smith
- Department of Physics, California State University-East Bay, Hayward, California 94542, USA
| | - Prasenjit Dey
- Department of Physics, University of South Florida, Tampa, Florida 33620, USA
| | - Varun Mapara
- Department of Physics, University of South Florida, Tampa, Florida 33620, USA
| | - Dimitry Semenov
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 30201, USA
| | - Steven A McGill
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 30201, USA
| | - Robert A Kaindl
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - David J Hilton
- Department of Physics, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | - Denis Karaiskaj
- Department of Physics, University of South Florida, Tampa, Florida 33620, USA
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Paul J, Stevens CE, Liu C, Dey P, McIntyre C, Turkowski V, Reno JL, Hilton DJ, Karaiskaj D. Strong Quantum Coherence between Fermi Liquid Mahan Excitons. PHYSICAL REVIEW LETTERS 2016; 116:157401. [PMID: 27127985 DOI: 10.1103/physrevlett.116.157401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Indexed: 06/05/2023]
Abstract
In modulation doped quantum wells, the excitons are formed as a result of the interactions of the charged holes with the electrons at the Fermi edge in the conduction band, leading to the so-called "Mahan excitons." The binding energy of Mahan excitons is expected to be greatly reduced and any quantum coherence destroyed as a result of the screening and electron-electron interactions. Surprisingly, we observe strong quantum coherence between the heavy hole and light hole excitons. Such correlations are revealed by the dominating cross-diagonal peaks in both one-quantum and two-quantum two-dimensional Fourier transform spectra. Theoretical simulations based on the optical Bloch equations where many-body effects are included phenomenologically reproduce well the experimental spectra. Time-dependent density functional theory calculations provide insight into the underlying physics and attribute the observed strong quantum coherence to a significantly reduced screening length and collective excitations of the many-electron system.
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Affiliation(s)
- J Paul
- Department of Physics, University of South Florida, 4202 East Fowler Avenue, Tampa, Florida 33620, USA
| | - C E Stevens
- Department of Physics, University of South Florida, 4202 East Fowler Avenue, Tampa, Florida 33620, USA
| | - C Liu
- Department of Physics, University of South Florida, 4202 East Fowler Avenue, Tampa, Florida 33620, USA
| | - P Dey
- Department of Physics, University of South Florida, 4202 East Fowler Avenue, Tampa, Florida 33620, USA
| | - C McIntyre
- Department of Physics, University of South Florida, 4202 East Fowler Avenue, Tampa, Florida 33620, USA
| | - V Turkowski
- Department of Physics, University of Central Florida, Orlando, Florida 32816, USA
| | - J L Reno
- CINT, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - D J Hilton
- Department of Physics, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | - D Karaiskaj
- Department of Physics, University of South Florida, 4202 East Fowler Avenue, Tampa, Florida 33620, USA
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Fractionally charged skyrmions in fractional quantum Hall effect. Nat Commun 2015; 6:8981. [PMID: 26608906 PMCID: PMC4674824 DOI: 10.1038/ncomms9981] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2015] [Accepted: 10/22/2015] [Indexed: 11/17/2022] Open
Abstract
The fractional quantum Hall effect has inspired searches for exotic emergent topological particles, such as fractionally charged excitations, composite fermions, abelian and nonabelian anyons and Majorana fermions. Fractionally charged skyrmions, which support both topological charge and topological vortex-like spin structure, have also been predicted to occur in the vicinity of 1/3 filling of the lowest Landau level. The fractional skyrmions, however, are anticipated to be exceedingly fragile, suppressed by very small Zeeman energies. Here we show that, slightly away from 1/3 filling, the smallest manifestations of the fractional skyrmion exist in the excitation spectrum for a broad range of Zeeman energies, and appear in resonant inelastic light scattering experiments as well-defined resonances slightly below the long wavelength spin wave mode. The spectroscopy of these exotic bound states serves as a sensitive tool for investigating the residual interaction between composite fermions, responsible for delicate new fractional quantum Hall states in this filling factor region. It is predicted that fractionally charged skyrmions, topologically protected vortex-like spin configurations, may exist in systems exhibiting fractional quantum Hall states. Here, the authors demonstrate the existence of such objects in GaAs single quantum wells.
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Paul J, Dey P, Tokumoto T, Reno JL, Hilton DJ, Karaiskaj D. Exploring two-dimensional electron gases with two-dimensional Fourier transform spectroscopy. J Chem Phys 2014; 141:134505. [PMID: 25296819 DOI: 10.1063/1.4896777] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The dephasing of the Fermi edge singularity excitations in two modulation doped single quantum wells of 12 nm and 18 nm thickness and in-well carrier concentration of ∼4 × 10(11) cm(-2) was carefully measured using spectrally resolved four-wave mixing (FWM) and two-dimensional Fourier transform (2DFT) spectroscopy. Although the absorption at the Fermi edge is broad at this doping level, the spectrally resolved FWM shows narrow resonances. Two peaks are observed separated by the heavy hole/light hole energy splitting. Temperature dependent "rephasing" (S1) 2DFT spectra show a rapid linear increase of the homogeneous linewidth with temperature. The dephasing rate increases faster with temperature in the narrower 12 nm quantum well, likely due to an increased carrier-phonon scattering rate. The S1 2DFT spectra were measured using co-linear, cross-linear, and co-circular polarizations. Distinct 2DFT lineshapes were observed for co-linear and cross-linear polarizations, suggesting the existence of polarization dependent contributions. The "two-quantum coherence" (S3) 2DFT spectra for the 12 nm quantum well show a single peak for both co-linear and co-circular polarizations.
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Affiliation(s)
- J Paul
- Department of Physics, University of South Florida, 4202 East Fowler Ave., Tampa, Florida 33620, USA
| | - P Dey
- Department of Physics, University of South Florida, 4202 East Fowler Ave., Tampa, Florida 33620, USA
| | - T Tokumoto
- Department of Physics, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | - J L Reno
- CINT, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - D J Hilton
- Department of Physics, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | - D Karaiskaj
- Department of Physics, University of South Florida, 4202 East Fowler Ave., Tampa, Florida 33620, USA
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Rhone TD, Majumder D, Dennis BS, Hirjibehedin C, Dujovne I, Groshaus JG, Gallais Y, Jain JK, Mandal SS, Pinczuk A, Pfeiffer L, West K. Higher-energy composite fermion levels in the fractional quantum Hall effect. PHYSICAL REVIEW LETTERS 2011; 106:096803. [PMID: 21405644 DOI: 10.1103/physrevlett.106.096803] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Indexed: 05/30/2023]
Abstract
Even though composite fermions in the fractional quantum Hall liquid are well established, it is not yet known up to what energies they remain intact. We probe the high-energy spectrum of the 1/3 liquid directly by resonant inelastic light scattering, and report the observation of a large number of new collective modes. Supported by our theoretical calculations, we associate these with transitions across two or more composite fermions levels. The formation of quasiparticle levels up to high energies is direct evidence for the robustness of topological order in the fractional quantum Hall effect.
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Affiliation(s)
- Trevor D Rhone
- Department of Physics, Columbia University, New York, New York 10027, USA
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Murthy G. Hamiltonian theory of disorder at nu = 1/3. PHYSICAL REVIEW LETTERS 2009; 103:206802. [PMID: 20365998 DOI: 10.1103/physrevlett.103.206802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2009] [Indexed: 05/29/2023]
Abstract
The Hamiltonian theory of the fractional quantum Hall regime provides a simple and tractable approach to calculating gaps, polarizations, and many other physical quantities. In this Letter we include disorder in our treatment and show that a simple model with minimal assumptions produces results consistent with a range of experiments. In particular, the interplay between disorder and interactions can result in experimental signatures which mimic those of spin textures.
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Affiliation(s)
- Ganpathy Murthy
- Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506-0055, USA.
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Affiliation(s)
- Steven H. Simon
- Rudolf Peierls Centre for Theoretical Physics, Unversity of Oxford, Oxford OX1 3NP, UK
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Hen I, Karliner M. Baby Skyrmions on the two-sphere. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 77:036612. [PMID: 18517548 DOI: 10.1103/physreve.77.036612] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2007] [Revised: 01/15/2008] [Indexed: 05/26/2023]
Abstract
We find the static multisoliton solutions of the baby Skyrme model on the two-sphere for topological charges 1< or =B< or =14. Numerical full-field results show that the charge-one Skyrmion is spherical, the charge-two Skyrmion is toroidal, and Skyrmions with higher charge all have point symmetries which are subgroups of O(3). We find that a rational map ansatz yields very good approximations to the full-field solutions. We point out a strong connection between the discrete symmetries of our solutions and those of corresponding solutions of the three-dimensional Skyrme model.
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Affiliation(s)
- Itay Hen
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv, Israel.
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