Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userPolaron-Polaritons in the Integer and Fractional Quantum Hall Regimes
71
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Elementary quasi-particles in a two dimensional electron system can be described as exciton-polarons since electron-exciton interactions ensures dressing of excitons by Fermi-sea electron-hole pair excitations. A relevant open question is the modification of this description when the electrons occupy flat-bands and electron-electron interactions become prominent. Here, we perform cavity spectroscopy of a two dimensional electron system in the strong-coupling regime where polariton resonances carry signatures of strongly correlated quantum Hall phases. By measuring the evolution of the polariton splitting under an external magnetic field, we demonstrate the modification of electron-exciton interactions that we associate with phase space filling at integer filling factors and polaron dressing at fractional filling factors. The observed non-linear behavior shows great promise for enhancing polariton-polariton interactions.
rate research
Read More
We report measurements of resistance oscillations in micron-scale antidots in both the integer and fractional quantum Hall regimes. In the integer regime, we conclude that oscillations are of the Coulomb type from the scaling of magnetic field period with the number of edges bound to the antidot. Based on both gate-voltage and field periods, we find at filling factor { u} = 2 a tunneling charge of e and two charged edges. Generalizing this picture to the fractional regime, we find (again, based on field and gate-voltage periods) at { u} = 2/3 a tunneling charge of (2/3)e and a single charged edge.
Quantum Hall (QH) edge channels appear not only along the edge of the electron gas but also along an interface between two QH regions with different filling factors. However, the fundamental transport characteristics of such interface channels are not well understood, particularly in the high-frequency regime. In this study, we investigate the interface plasmon mode along the edge of a metal gate electrode with ungated and gated QH regions in both integer and fractional QH regimes using a time-resolved measurement scheme. The observed plasmon waveform was delayed and broadened due to the influence of the charge puddles formed around the channel. The charge velocity and diffusion constant of the plasmon mode were evaluated by analyzing the waveform using a distributed circuit model. We found that the conductive puddles in the gated region induce significant dissipation in plasmon transport. For instance, a fractional interface channel with a reasonably fast velocity was obtained by preparing a fractional state in the ungated region and an integer state in the gated region, whereas a channel in the swapped configuration was quite dissipative. This reveals a high-quality interface channel that provides a clean path to transport fractional charges for studying various fractional QH phenomena.
Protected edge modes are the cornerstone of topological states of matter. The simplest example is provided by the integer quantum Hall state at Landau level filling unity, which should feature a single chiral mode carrying electronic excitations. In the presence of a smooth confining potential it was hitherto believed that this picture may only be partially modified by the appearance of additional counterpropagating integer-charge modes. Here, we demonstrate the breakdown of this paradigm: The system favors the formation of edge modes supporting fractional excitations. This accounts for previous observations, and leads to additional predictions amenable to experimental tests.
Electronic systems harboring one dimensional helical modes, where the spin and momentum of the electron are locked, have lately become an important field of its own. When coupled to a conventional superconductor, such systems are expected to manifest topological superconductivity, a unique phase that gives rise to exotic Majorana zero modes. Even more interesting are fractional helical states which have not been observed before and which open the route for the realization of the generalized para fermions quasiparticles. Possessing non abelian exchange statistics, these quasiparticles may serve as building blocks in topological quantum computing. Here, we present a new approach to form protected one dimensional helical and fractional helical edge modes in the quantum Hall regime. The novel platform is based on a carefully designed double quantum well structure in a high mobility GaAs based system. In turn, the quantum well hosts two sub bands of 2D electrons, each tuned to the quantum Hall effect regime. By electrostatic gating of different areas of the structure, counter propagating integer, as well as fractional, edge modes, belonging to Landau levels with opposite spins are formed, rendering the modes helical. We demonstrate that due to spin protection, these helical modes remain ballistic, without observed mixing for large distances. In addition to the formation of helical modes, this new platform can be exploited as a rich playground for an artificial induction of compounded fractional edge modes, as well as construction of interferometers based on chiral edge modes.
We propose ways to create and detect fractionally charged excitations in emph{integer} quantum Hall edge states. The charge fractionalization occurs due to the Coulomb interaction between electrons propagating on different edge channels. The fractional charge of the soliton-like collective excitations can be observed in time resolved or frequency dependent shot noise measurements.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
