Graphene Under Ultrafast LASER: An Avenue For Quantum Technologies

2023-09-20 Dr. Gopal Dixit

ABSTRACT :

Analogues to spin, electrons in graphene endow an additional quantum attribute: valley pseudospin, which is associated with the two degenerate valleys in the energy landscape of graphene. Similar to 0 and 1, two valleys can be seen as two units of operations. Not only that, operations in between the two units, i.e., the superposition of 1 and 0, can also be realised using two valleys. Thus, these valleys have potential to encode, process, and store quantum information at room temperature – A holy grail for quantum computing.

In this talk, I will discuss how valley-selective excitation in graphene with zero bandgap can be achieved by an all-optical means. Ultrashort laser pulses are employed to obtain a desire control over valley polarisation. By tailoring the waveforms of the laser pulses to the symmetry of the graphene’s sub-lattice, first I will demonstrate that it is possible to induce and read valley polarization in graphene – a medium where light-driven valleytronics was thought to be impossible. In the later part of this talk, I will show a coherent protocol to initiate valley-selective excitation, de-excitation and switch the excitation to another valley within tens of femtoseconds. Coherent switching of electronic excitation from one valley to another on a timescale faster than the valley decoherence is quintessential for valleytronics-based emerging quantum technologies at ambient conditions.

Event Name

Seminars

Place

HSB 210 (Bose Hall)

Start Time

15:00

End Time

External Link

PDF to Talk