Leonardo Valente, MSc Physics at ETH Zürich
Alexander Roth, MSc Physics at ETH Zürich, Research Assistant at Max Planck Institute for Quantum Optics
Bartłomiej Leks, MSc Material Science ETH Zürich
Decoherence in Quantum Reference Frames (Leonardo Valente):
We explore the phenomenon of decoherence and how it changes under quantum reference frame (QRF) transformations. In particular, we simulate how gravitationally induced decoherence depends on the chosen QRF. In our model, we find that if a massive particle decoheres smoothly over a finite timescale in one QRF, then from the particle’s own QRF, the decoherence appears instantaneous. We analyse this asymmetry and show, using entropy-based tools, that it does not arise from the existence of a privileged QRF. Additionally, we introduce the notion of non-entangling states — a class of states that preserve entanglement and maintain the tensor product structure under QRF transformations — as a way to keep coherence frame-independent.
Constructing N -Dimensional Unitaries From Local Gates: Enabling Efficient1 Rearrangement and Fourier Transforms (Alexander Roth):
A major challenge in neutral-atom quantum simulation is control. Our experimental tools are local, allowing us to “talk to” one or two atoms, but our algorithms demand complex global operations. How can we bridge this gap?
In this talk, I’ll present a systematic recipe for compiling any desired global, single-particle operation into a practical sequence of simple local “tunneling” and “phase-shift” gates.
I’ll then show this recipe in action for two key examples: the Discrete Fourier Transform (DFT) and parallel atom sorting. We will see how to extend these ideas to two dimensions, resulting in a 2D atom rearrangement protocol that scales sub-linearly with the total number of atoms. This provides a solution to a major bottleneck for scaling up these quantum platforms.
1D Chains as a Window into Fractionalized Graphene States (Bartłomiej Leks):
At one-third filling, twisted bilayer graphene is predicted to host fractionalized excitations with restricted mobility – so-called fractons. These quasiparticles are unusual in two dimensions, but certain low-energy limits suggest they could appear, motivating simplified models to understand the underlying physics.
In this talk, I will focus on a one-dimensional analog of the proposed “brick-wall” correlated state. This system, with strong cluster charging and longer-range attractive interactions, already shows rich physics: conventional Fermi-liquid behavior gives way to a Luttinger liquid, which at stronger interactions undergoes phase separation. I will explain how Bethe ansatz, bosonization, and DMRG can be used to analyze these behaviors, connecting analytical predictions with numerical results.
I will briefly discuss how these 1D insights might inform our understanding of higher-dimensional systems and fractionalization – how relatively simple 1D models can reveal fundamental mechanisms behind correlated and constrained quantum states.
Recording
The talk will be streamed and there will be a (partial) recording.