A cryogenic optical cavity for trapped Yb+ quantum networking
Abstract: One approach to ion-photon entanglement relies on transitions from 2P3/2 to the low-lying 2D3/2 and 2D5/2 states at 1345 nm and 1650 nm in Yb+ [1]. Here Purcell enhancement is crucial for achieving good performance in the context of quantum networking. In support of this effort, we developed a monolithic, fiber-coupled Fabry–Pérot cavity integrated with a blade trap that operates at cryogenic temperatures. One of the cavity mirrors is bonded to a metalens that mode-matches cavity light to a single-mode fiber.
Anyone for Anyons?
Researchers have demonstrated that a strange type of quantum particle called the anyon, believed to exist in only two dimensions, can also be created in one dimension. Further studies exploring different types of one-dimensional anyons could bring scientists one step closer to using the particles as a fundamental unit of memory in a quantum computer.
The Rayleigh-Taylor instability in a binary quantum fluid
Abstract: Instabilities, where initially small fluctuations seed the formation of large-scale structures, govern the dynamics in various fluid flows. The Rayleigh-Taylor instability (RTI) is an iconic example that leads to the development of mushroom-shaped incursions when immiscible fluids are accelerated into each other. RTI drives structure formation throughout science and engineering including table-top oil and water mixtures; supernova explosions; and inertial confinement fusion. Despite its ubiquity, controlled laboratory RTI experiments are technically challenging.
International Year of Quantum Science and Technology
To mark a century of progress in quantum science, the United Nations General Assembly has declared 2025 to be the International Year of Quantum Science and Technology (IYQ). To celebrate the occasion, governments, professional societies, academic institutions and many others will be sharing the story of quantum science—its past, present and future—with audiences around the world.
JQI is excited to join in the fun, and we will share our events and initiatives here and on our social media channels. Some notable events are:
A Constructive Approach to Zauner’s Conjecture via the Stark Conjectures
Abstract: In this talk, I will present a construction of symmetric informationally complete POVMs (SIC-POVMs), a special class of quantum measurements whose existence in all dimensions was conjectured by Zauner in 1999. Equivalently, these are maximal sets of d^2 equiangular lines in ℂ^d. Our approach introduces an explicit mathematical object, the ghost SIC, built from number-theoretic properties of a special modular function, and we show that it is Galois conjugateto an actual SIC.
Glasses: From Physical Hamiltonians to Neural Networks and Back
Abstract: This talk will review our recent work on classical and quantum glasses. I will start with a discussion of spin glasses from the perspective of chaos theory.
Conditional lower bounds for algorithms with pre-processed advice
Abstract: Unlike the traditional study of algorithms which attempts to solve a certain task using minimal space and time resources, I will discuss data structures to solve certain algorithmic tasks after an initial pre-processing phase. The interest here is to study the tradeoffs between the resources such as the space and time required to perform the algorithmic task when asked a query; and the resources in the pre-processing phase such as the time required to prepare the data structure or its size.
Universal Adapters between quantum LDPC codes
Abstract: Error-correction is key to building a quantum computer. This includes both storage of quantum information as well as computing on it. Quantum low- density parity check (LDPC) codes offer a route to build these devices with low space overhead. The next question is - how do we fault-tolerantly com- pute on these codes? Existing proposals (Cohen et al. [2110.10794], Cross et al. [2407.18393]) rely on ancilla systems appended to the original LDPC code.
Permutation-invariant quantum error correction codes: from theory to practice
Abstract: Permutation-invariant quantum error correction codes that are invariant under any permutation of the underlying particles. These codes could have potential applications in quantum sensors and quantum memories. Here I will review the field of permutation-invariant codes, from code constructions to applications.
*We strongly encourage attendees to use their full name (and if possible, their UMD credentials) to join the zoom session.*