Ultrafast nonlinear optical response of strongly correlated systems: Dynamics in the quantum Hall effect regime

Karathanos, A. T.; Perakis, I. E.; Fromer, Neil A.; Chemla, D. S.

doi:10.1103/physrevb.67.035316

Cited by 29 publications

(109 citation statements)

References 55 publications

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“…States with 3 n ≥ do not contribute to third-order [7]. The linear response is described by the time evolution of the 1-h many-body state 1 | L ψ Ò calculated to first order in the optical field.…”

Section: ]mentioning

confidence: 99%

“…n n Y X · Ò and ˆn Y · Ò up to third order in the optical fields [7,9]. To achieve this, we first decompose these density matrices into correlated and uncorrelated contributions, which allows us to identify the experimental signature of the correlations and devise approximations.…”

Section: ]mentioning

confidence: 99%

“…X is the dipole interband transition operator [7,9]. We consider right-circularly polarized optical pulses (σ + ), which excite only spin-↓ electrons, and consider filling factors close to 1 ν ∼ , where the ground state is predominantly populated by spin-↑ LL0 electrons.…”

Section: Polarization and Carrier Population Equations Of Motionmentioning

confidence: 99%

“…We use the standard two-band Hamiltonian H that describes discrete LLs coupled by the Coulomb interactions [7,9,17]. The coupling of the optical field is characterized by the Rabi energy ( )…”

Section: Polarization and Carrier Population Equations Of Motionmentioning

confidence: 99%

“…Such MPs have been observed in inelastic light scattering [2][3][4] and other experiments. However, their role during the early timescales of quantum coherent dynamics in the QH system is just beginning to be explored [6][7][8][9][10]. In general, coherences play a central role in several quantum mechanical systems [11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

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Correlation effects in the ultrafast dynamics of the Quantum Hall system close to v = 1

Kavousanaki¹,

Dani²,

Tignon³

et al. 2006

Physica Status Solidi (b)

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We present a many-body theory of the non-linear optical response of the Quantum Hall system. This theory describes the role of the cold, strongly correlated, two-dimensional electron gas (2DEG) in the ultrafast dynamics. We discuss the manifestations of intraband and interband coherences induced by the collective 2DEG excitations in the coupled photocarrier -Quantum Hall system. We compare to transient three-pulse four-wave-mixing experiments.

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Section: ]mentioning

confidence: 99%

Section: ]mentioning

confidence: 99%

Section: Polarization and Carrier Population Equations Of Motionmentioning

confidence: 99%

Section: Polarization and Carrier Population Equations Of Motionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Correlation effects in the ultrafast dynamics of the Quantum Hall system close to v = 1

Kavousanaki¹,

Dani²,

Tignon³

et al. 2006

Physica Status Solidi (b)

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Ultrafast Dephasing and Collective Effects in the Quantum Hall Effect Regime

Perakis

Chemla

2002

phys. stat. sol. (b)

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Dedicated to Professor Dr. Roland Zimmermann on the occasion of his 60th birthday Using time resolved four-wave-mixing (FWM) spectroscopy and many-body theory we investigate the role of non-instantaneous collective and correlation effects in the dynamics of the cold two dimensional electron gas (2DEG) in large magnetic fields. We find a strong non-Markovian magnetoexciton dephasing and a strong time-dependent Coulomb coupling between the Landau levels (LL), governed by the dynamics of the inter-LL magnetoplasmon (MP) excitations. Our results show that ultrafast spectroscopy is a powerful tool for studying collective and strong correlation effects on the nanoscale. IntroductionCollective effects on the nanometer and femtosecond scale present a frontier problem of condensed matter physics [1-6]. Well-established pictures need to be revised, such as the semiclassical Boltzmann picture of dephasing and relaxation [2, 5-7] and the Random Phase Approximation (RPA) description of the interactions among the photoexcited quasiparticles [1,2]. Transient wave-mixing spectroscopy is ideally suited for exploring such correlation effects, as fluctuations beyond the RPA generate a FWM signal with distinct time and frequency dependence [1, 2]. In undoped semiconductors, the lowest electronic excitations of the ground state electrons are the high energy interband e-h pair excitations, which can adjust almost instantaneously to the dynamics of the photoexcited carriers. The latter then behave as quasiparticles with mutual interactions, while the ground state can be considered as rigid: the many-body nature of the system only affects the different parameters associated with the band structure and the dielectric screening. As a result, the role of the Coulomb correlations can be studied by using theoretical approaches such as the ''dynamics-controlled truncation scheme" (DCTS) [8], which assume that all Coulomb interactions occur between photoexcited e-h pairs and are thus dynamically generated by the optical excitation.The DCTS, however, assumes the absence of free carriers in the ground state [8], a condition that does not hold in modulation-doped quantum wells (MDQWs) with a cold 2DEG in the ground state. The almost unexplored dynamics of strongly correlated systems, whose ground state electrons interact unadiabatically with the photo-excited

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Ultrafast dephasing in strongly correlated systems

Perakis¹

2003

Physica Status Solidi (b)

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Using projection techniques we derive the equation of motion for the third-order nonlinear optical polarization of a strongly correlated system. We do not assume a Hartree-Fock ground state, but include the ground state correlations via time-independent interaction parameters and energies. Our theory can be used to describe the ultrafast nonlinear optical response of a strongly correlated cold electron gas, such as the two-dimensional electron gas in the quantum Hall effect regime. For this system, we show that the collective electronic excitations lead to a time-dependent coupling of the Landau level magnetoexcitons and a strong non-Markovian exciton dephasing. We discuss the signatures in the transient four-wave-mixing spectrum. . Most efforts so far have focussed on undoped semiconductors, where the lowest electronic excitations are the high energy interband e-h pair excitations that behave as quasiparticles with mutual interactions. In the absence of low lying electronic excitations, the ground state can be considered as rigid, and is usually described within the Hartree-Fock approximation. As a result, in undoped semiconductors, the role of the Coulomb correlations in the ultarafast nonlinear response can be studied in an exact fashion by using, e.g., the ''dynamics-controlled truncation scheme" (DCTS) [2].The DCTS considers a system with a Hartree-Fock ground state and assumes the absence of free carriers prior to the optical excitation [2]. Here we are interested in systems such as modulation-doped quantum wells (MDQWs) in a strong magnetic field, where a strongly correlated two-dimensional electron gas (2DEG) is already present in the ground state. The almost unexplored dynamics of strongly correlated systems, whose ground state electrons interact unadiabatically with the photo-excited e-h pairs, raises very fundamental questions. In MDQWs, the direct exciton-exciton interactions are screened. In the absence of magnetic field, the coherent nonlinear optical response was studied in Refs. [3,4] and shown to be strongly influenced by the interactions between the photoexcited carriers and the Fermi sea excitations.The role of the Coulomb correlations becomes more pronounced when a magnetic field is applied to the 2DEG in MDQWs, in a direction perpendicular to the quantum well plane. The energy

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Ultrafast nonlinear optical response of strongly correlated systems: Dynamics in the quantum Hall effect regime

Cited by 29 publications

References 55 publications

Correlation effects in the ultrafast dynamics of the Quantum Hall system close to v = 1

Correlation effects in the ultrafast dynamics of the Quantum Hall system close to v = 1

Ultrafast Dephasing and Collective Effects in the Quantum Hall Effect Regime

Ultrafast dephasing in strongly correlated systems

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