Fall 2025

September 12, 2025 (Friday) 4:00-5:00 p.m.
Location: Small Hall 111 
Speaker: Shengwang Du
Host: Irina Novikova 

Title: Distributed Quantum Computing with Shared Quantum Gate Processing Unit 
Abstract: Due to many physical constraints, it is extremely challenging to build a monolithic fully connected quantum computer with a very large number (N) of qubits, in which a direct control gate operation can be performed between two arbitrary qubits. Extending from N to N+1 in such a quantum computer is more than just physically adding one more qubit. For this reason, the cost of such a fully connected quantum computer increases exponentially as the number of qubits increases. On the other side, connecting two N-qubit remote quantum computers classically, the dimension of their combined Hilbert space is only 2´2^N=2^(N+1). If they are fully connected though quantum links, the dimension of the combined Hilbert space could reach 2^(2N) which is much more powerful than two independent quantum computers. Consequently, there is a growing interest in exploring distributed quantum computing (DQC) systems that can interconnect many small-sized, cost-effective local quantum computers. In most conventional DQC architectures, each local quantum computer is equipped with additional communication qubits dedicated to establishing remote entanglement links. The presence of these communication qubits not only substantially increases the cost of individual local quantum computer nodes, but also renders the entanglement-communication-based scheme inherently non-deterministic. In this work, we propose a DQC architecture in which individual small-sized quantum computers are connected through a shared quantum gate processing unit (S-QGPU) [1]. The S-QGPU comprises a collection of hybrid two-qubit gate modules [2] for remote gate operations. In contrast to conventional entangled-communication-based DQC systems, S-QGPU effectively pools the resources together for remote gate operations, and thus significantly reduces the cost of not only the local quantum computers but also the overall distributed system. Moreover, S-QGPU's shared resources for remote gate operations enable efficient resource utilization. When not all computing qubits in the system require simultaneous remote gate operations, S-QGPU-based DQC architecture demands fewer resources, further decreasing the overall cost. Unlike conventional DQC architectures based on entanglement communication, wherein remote gate operations are accomplished via teleportation or cat-entanglers [3, 4], the proposed S-QGPU approach for remote gate operations is deterministic and does not depend on any measurement-based post selection.

September 26, 2025 (Friday) 4:00-5:00 p.m.
Location: Small Hall 111 
Speaker: Alex Kamenev
Host: Enrico Rossi  

Title: Quantum Computation: Myths and Reality
Abstract: The talk has dual goals: (i) to illustrate that available quantum platforms may be used to implement meaningful computational tasks, such as optimization, image recognition, and training of neural networks; (ii) to argue that this fact raises fundamental theoretical questions, e.g.,  of limits on computational complexity of these tasks, of universality classes in many-body dynamics of partially-coherent quantum systems, along with many others.

October 3, 2025 (Friday) 4:00-5:00 p.m.
Location: Small Hall 111 
Speaker: Robert-Jan Slager
Host: Enrico Rossi 

Title: Quantum Geometry Beyond Single Flat Bands and Euler Exact Projected Entangled Pair Ground States
Abstract: The past few years have seen a revived interest in quantum geometrical characterizations. Although the metric tensor has been connected to many geometrical concepts for single bands, the exploration of these concepts to a multi-band paradigm still promises a new field of interest. I will discuss a new route involving Pl\"ucker embeddings to represent arbitrary classifying spaces, being the essential objects that encode all the relevant topology for any multi-band system. While I will argue that this tool can be applied in contexts that range from response theories to finding quantum volumes and bounds on superfluid densities as well as possible quantum computations, I will in particular also show that they can be used to formulate projector Hamiltonians with projected entangled pair ground (PEPS) states that have a finite topological invariant, the Euler class, circumventing many no-go theorems. We further demonstrate the versatility of our model states by applying a shallow quantum circuit, producing interacting PEPS and simple parent Hamiltonians in the Euler phase. These model states moreover pinpoint to new interacting physics.

October 24, 2025 (Friday) 4:00-5:00 p.m.
Location: Small Hall 111 
Speaker: John Hardin
Host: Justin Stevens

Title: The Flavored Milky Way

 Abstract: IceCube is a neutrino telescope built into the ice at the south pole.  The detector is sensitive to "tracks" as produced by charged current interactions from muon neutrinos and "cascades" produced by other flavors and the neutral current.  Due to recent machine-learning-based advances in reconstruction, the precision of the pointing and background rejection have improved significantly, and IceCube has been able to detect neutrino emission from the Galactic Plane.  Since this detection, it has become possible to probe the flavor content of this excess which opens up additional probes of BSM physics.  IceCube as a detector, the recent Galactic Plane result, and the use of IceCube as a vehicle to detect Beyond the Standard Model Physics are discussed. 

October 31, 2025 (Friday) 4:00-5:00 p.m.
Location: Small Hall 111 
Speaker: Herbert Fertig
Host: Enrico Rossi 

Title: Neutral Modes of Electrons and Their Quantum Geometry
Abstract: Electrons in solids possess quantum geometric structure that have measurable consequences for the materials in which they are embedded.   In this colloquium I will introduce the general ideas behind this concept, and how it can be applied to neutral, collective modes of electronic materials.  From this approach we find that generically these excitations possess their own type of geometric property: a “quantum geometric dipole” (QGD).  I will focus on two examples in which a QGD can appear: excitons – bound particle-hole pairs akin to hydrogen atoms; and plasmons – quantized electron density oscillations.  In both cases a non-zero QGD implies internal structure in the excitation, in the form of a non-vanishing average electrical dipole moment.  I will discuss the conditions under which an excitation hosts a non-vanishing QGD, and some possibilities for physical phenomena which may result from it.

November 14, 2025 (Friday) 4:00-5:00 p.m.
Location: Small Hall 111 
Speaker: Sophia Economou
Host: Irina Novikova

Title: Spin-photon interfaces: control and distribution of entanglement
Abstract: Spin-photon interfaces are ubiquitous in quantum information processing and also feature intriguing physics culminating from the interplay of spin-spin, spin-photon, and spin--control-field interactions. In these systems, of particular interest are entangled states of nuclear spins, which can be used as quantum memories, and of photonic qubits, which can be used to transmit information robustly. I will discuss the dynamics of these systems and applications to quantum networks and photonic quantum computing.

 

November 21, 2025 (Friday) 4:00-5:00 p.m.
Location: Small Hall 111 
Speaker: Navin McGinnis
Host: Andrew Jackura 

Title: The Origin of Symmetry from Quantum Information
Abstract: Few questions cut as deeply across the history of science as whether symmetry is fundamental or emergent. For Plato, symmetry represented timeless perfection; for Aristotle, it was an emergent property, arising from our attempts to describe Nature. This tension still remains alive today in our understanding of symmetries that underlie the laws of particle physics. Recently, a number of hints have suggested that these symmetries may emerge from principles of quantum information. Demonstrative examples appear in low-energy Quantum Chromodynamics, the Standard Model quark flavor sector, and in models beyond Standard Model. In this colloquium, I will explore this possibility through the lens of It from Bit, the idea that physical law may be rooted in information-theoretic principles. Building on recent work, I will describe a purely S-matrix approach that ties these observations together from basic principles of quantum field theory and scattering theory. I will conclude with prospects for developing new information-theoretic principles for the S-matrix, which may reshape how we think about the foundations of particle physics.