DQMP Forum - Unprecedented Control of Band Structure: Quenching the Band Gap of a 2D Semiconductor with Colossal Electric Fields - Transport in Quantum Many-body Systems under Continuous Measurement

15.06.2021 13:00 – 14:00

Unprecedented Control of Band Structure: Quenching the Band Gap of a 2D Semiconductor with Colossal Electric Fields
Daniil Domaretskiy (group of prof. Morpurgo)

Band structure engineering and control has been a great interest in science for decades. One of the key tools of tuning band structure –application of a perpendicular electric field– led to a gap opening in a gapless semiconductor such as bilayer graphene. However, employment of the same principle to a wider palette of materials has been prevented due to the infeasibility of sufficiently large electric fields. In this talk, I present a technique to create electric fields of colossal strength that we realize with a new type of devices based on a double ionic gate configuration. Using this approach, we demonstrate an unprecedented control of the band structure of a few-layer TMDs by continuously tuning the band gap from 1.5 eV to 0.


Transport in Quantum Many-body Systems under Continuous Measurement
Tony Jin Zizhuo (group of prof. Giamarchi)

Measurement is not a benign act in quantum mechanics and has an e↵ect on the system called the backaction. In this talk, I’ll show how transport properties in many-body quantum systems are a↵ected by such measurement backaction.
Famously, a system under continuous and strong measurement is repeatedly projected onto a single eigenstate. This is known as the quantum Zeno e↵ects. However, at long enough time scales, the system can jump between the eigenstates of the measured observable, introducing a rich dynamics at a slower time scale. After introducing the concepts of continuous monitoring and quantum trajectories, I will present such e↵ective dynamics for a XX spin chain and a system of free bosons and show that they are respectively described by the symmetric simple exclusion process and the misanthrope process in the strong monitoring regime, two well-known models of classical statistical physics model.

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