CQT is seeking Research Fellows, Research Assistants and PhD students to join projects across the Centre.
CQT researchers propose method to do covert quantum communication
The Centre marked its 9th birthday and presented staff awards at end-of-year events
- CQT PhD Thesis Oral Defense by Debashis De Munshi — 20 Jan, 04:00 PM
- CQT Colloquium by Fernando Pastawski, Institute for Quantum Information and Matter (IQIM) — 02 Feb, 04:00 PM
CQT PhD Thesis Oral Defense by Debashis De Munshi
Title: Precision Measurements to Explore Underlying Geometries and Interactions in a Trapped Ba+ ion
Date/Time: 20 Jan, 04:00 PM
Venue: CQT Level 3 Conference Room, S15-03-18
The work described in this thesis consists of both theoretical and experimental research performed on single trapped ion. The barium ion, being a heavy multi-electron system, allows benchmarking of highly demanding ab-initio many body electronic structure calculations. The dipole forbidden tran sitions in barium ion also serves as a test bed for atomic parity non-<:onservation, geometric phase generation, optical qubit, etc.
In this work, the possibility of measuring and quantifying geoemtric phase in two different symmery of the underlying Harnitonian has been studied. This study leads to the prospect of using dipole forbidden transition in barium ion as its possible test bed. However, it is essential to measure the quadrupole shift of this transition before implementing the geometric phase measurement protocol. In the experimental section of this thesis, precision measurement on the allowed dipole transi tion has been performed to benchmark the many body calculations required to study atomic parity non-conservation in barium ion. Further experiments has been performed in order to measure the quadrupole shift of the dipole forbidden transition. These measurements firmly sets the foundations for future measurements to be performed on both atomic parity non-conservation and implementa tion of geometric phase generation proposals as developed in the theoretical part of the thesis.
This thesis contains a theoretical proposal to implement geometric phase generation protocol in a trapped barium ion using only electric fields. It further includes the first measurements of branching fraction of dipole allowed transition in barium ion with a precision well below 0.05% which allows us to discriminate between different many body calculations done with a precision of 1%. In ad dition, this thesis lays the foundation to measure the more challenging electric quadrupole shift of the dipole forbidden transition in barium ion. This led to implementation of a fast optical qubit at a wavelength close to telecommunication wavelength.
CQT Colloquium by Fernando Pastawski, Institute for Quantum Information and Matter (IQIM)
Title: Holographic quantum error-correcting codes
Date/Time: 02 Feb, 04:00 PM
Venue: CQT Level 3 Seminar Room, S15-03-15
Abstract: In this talk, I will explore the recent connection between two profound ideas, quantum error correction and holography. The first, represents the realization that reliable quantum information processing could be achieved from imperfect physical components. The second, is a duality between two physical systems on different spatial dimensions which may be identified leading to the exact same predictions. Notably, only one of the two systems explicit includes gravitational features. Recently, quantum information has emerged as a natural tool to relate these two descriptions. As such, concepts familiar to quantum information scientists such as entanglement, compression and quantum error correction are playing important roles in understanding this duality. Conversely, the holographic duality is proposing a new lens through which to explore aspects of quantum error correction. In this talk, I will introduce some of the properties imposed by holography on corresponding quantum error-correcting codes, describe explicit tensor network codes which exhibit some of these properties and explore the implications of holographic predictions from a code-theoretic perspective.