丁香园AV

Arrott Plot

Dedicated to Professor Emeritus Anthony Arrott

Revealing the Absence of Spontaneous Magnetic Fields in Bulk Superconducting UTe2 through Zero-Field Muon Spin Relaxation

This study presents a comprehensive investigation into the local magnetic properties of candidate odd-parity superconductor UTe2, specifically addressing the conjecture of time-reversal symmetry (TRS) breaking. Utilizing zero-field muon spin relaxation (碌SR), we examine molten salt-flux (MSF) grown single crystals of UTe2, contrasting with previous assessments on chemical vapor transport (CVT) grown crystals. Our results significantly diverge by demonstrating an absence of magnetic clusters or electronic moments that would indicate spontaneous magnetic fields consequential to

TRS breaking in the superconducting state. Such spontaneous fields are anticipated around impurities or lattice defects if present, hence suggesting a single-component superconducting order parameter for UTe2, contrary to expectations of TRS breaking tied to unconventional superconductivity.

Mirror Symmetry in the f7/2 Shell below 56Ni, Excited States and Electromagnetic Transition Rates in 55Ni and 55Co

Nuclear theories often operate under the assumption that the strong nuclear force is independent of electric charge. Therefore, it is expected that exchanging the number of protons with the number of neutrons in a nucleus will produce a mirror nucleus with identical structure after electromagnetic considerations. However, charge dependence in nuclear theories is required due to isospin non-conserving interactions and resulting effects like Mirror Energy Differences in excited states for mirror nuclei which cannot be resolved by Coulombic forces.

This charge dependence is being explored at TRIUMF, Canada鈥檚 national particle accelerator centre. A stable 20Ne beam experiment to produce 55Co was conducted with a complimentary radioactive 21Na beam experiment to produce 55Ni expected in 2024. Production of this mirror pair leverages the TRIUMF-ISAC Gamma-Ray Escape Suppressed Spectrometer (TIGRESS) for gammas, 丁香园AV鈥檚 TIGRESS Integrated Plunger for charged particles, 40Ca targetry, and the Doppler-Shift Attenuation Method for lifetimes. The 55Ni experiment will also utilize the Electromagnetic Mass Analyzer for A, Z, and E measurements of recoil nuclei for enhanced selectivity. This talk will discuss the state of the 55Co experiment analysis which currently focuses on characterizing extracted proton and alpha spectra with the Weisskopf model of evaporation to extract compound nucleus temperatures under varying conditions. Future analysis will explore the charge dependence of the strong interaction, the f7/2 hole configurations in 56Ni and electromagnetic transition rates for excited states of 55Ni and 55Co.

Downloading many-body entanglement from a continuous variable cluster state to a qubit cluster state

Generating the many-body entanglement in a qubit cluster state for a measurement based quantum computer is experimentally challenging. However, recent work has shown continuous-variable (CV) cluster states are a highly scalable, efficient source of generating many body entanglement. We present a hybrid CV-qubit approach to generate qubit cluster states, by downloading the entanglement from CV cluster states which can be more easily generated. Our protocol is hybrid CV-qubit quantum teleportation in the displaced Gottesman-Kitaev-Preskill (GKP) basis. In the equivalent CV circuit, weak conditional displacement and homodyne detection is sufficient to physically realize our protocol, which is available for a wide variety of platforms. Our results show that only 6dB squeezing is sufficient to protect the qubit quantum information, and 12dB of squeezing is sufficient for universal fault-tolerant quantum computation. Furthermore, we completely characterize the loss in our protocol, showing that finite squeezing error can be converted to qubit deletion and channel/detector loss becomes qubit dephasing. With a many-qubit per site model, the squeezing threshold can be further suppressed.

Deterministic Construction of Arbitrary States in Permutationally-Invariant Spin Ensemble

Atomic and solid-state spin ensembles are promising quantum technological platforms, but practical architectures are incapable of resolving individual spins. The state of an unresolvable spin ensemble must obey the condition of permutational invariance, yet no method of generating general permutationally-invariant (PI) states is known. In this work, we develop a systematic strategy to generate arbitrary PI states. Our protocol involves first populating specific effective angular momentum states with engineered dissipation, then creating superposition through a modified Law-Eberly scheme. We illustrate how the required dissipation can be engineered with realistic level structure and interaction. We also discuss possible situations that may limit the practical state generation efficiency and propose pulsed-dissipation strategies to resolve the issues. Our protocol unlocks previously inaccessible spin ensemble states that can be advantageous in quantum technologies, e.g. more robust quantum memory.

Engineering non-Gaussian bosonic gate through quantum signal processing

Non-Gaussian operations are essential for most bosonic quantum technologies. Yet, realizable non-Gaussian operations are rather limited in type and generally suffer from accuracy-duration tradeoffs. In this work, we propose to use quantum signal processing to engineer non-Gaussian operations. For systems dispersively coupled to an auxiliary qubit, our scheme can generate a new type of non-linear phase gate. Such gate is an extension of the selective number-dependent arbitrary phase (SNAP) gate, but an extremely high accuracy can be achieved within a reduced, fixed, excitation-independent interaction time. Our versatile formalism can also engineer operations for a variety of tasks, e.g. processing rotational symmetric codes, entangling qudits, and deterministically generating multi-component cat states

AGEing of Collagen: The Effects of Glycation on Collagen鈥檚 Stability, Mechanics and Self-Assembly

Advanced Glycation End Products (AGEs) are the end result of the irreversible, non-enzymatic glycation of proteins by reducing sugars. These chemical modifications accumulate with age and have been associated with various age-related and diabetic complications. AGEs predominantly accumulate on proteins with slow turnover rates, of which collagen is a prime example. Glycation has been found to lead to tissue stiffening and reduced collagen fibril turnover. In this study, we investigate the effects of glycation on the stability of type I collagen, its molecular-level mechanics and its ability to perform its physiological role of self-assembly. Collagen AGEing is induced in vitro by incubation with ribose. We confirm and assess glycation using auto-fluorescence measurements and changes in collagen's electrophoretic mobility. Susceptibility to trypsin digestion and circular dichroism (CD) spectroscopy are used to probe changes in collagen's triple helical stability. Atomic Force Microscopy (AFM) imaging quantifies how AGEing affects collagen flexibility. Finally, we use DIC microscopy to assess AGEd collagen鈥檚 ability to self-assemble into fibrils. These findings shed light on the molecular mechanisms underlying AGE-induced tissue changes, offering insight into how glycation modifies protein structure and stability.

Tunable domain wall motion in multi-domain spin structures in an ultracold 87Rb gas

We study domain wall motion in pseudo-spin-陆 ultracold 87Rb gas initialized in an 鈥榰p-down-up鈥� configuration. We measure domain wall velocities for various initial domain conditions and qualitatively distinguish two regimes of wall motion. At short times, transverse spin is confined to the domain walls, slowing down domain walls dynamics via exchange collisions. Later, coherence in the domain wall decreases, and the velocity of the wall increases. By studying the effects of initial coherence and transverse phase gradients in the domain wall on the wall dynamics, we identify controlling parameters and demonstrate the tunability of domain wall trajectories. We find that asymmetry in the spatiotemporal evolutions of initially symmetric longitudinal magnetization is related to asymmetry in phase gradients in the transverse magnetization. Numerical solutions of a quantum Boltzmann equation agree well with the measured wall trajectories. We also present progress toward using machine learning algorithms to predict conditions that lead to target domain wall motions.

*Note that two students will present one shared poster.

Doppler-shift attenuation lifetime measurement of the first-excited 2+ state in 36Ar

The strong force is the fundamental interactions that binds quarks into nucleons. The residual strong force, also known as the nuclear force, binds nucleons into nuclei. Nuclear models that aim to accurately describe and predict nuclear properties, such as energy levels and nuclear wavefunctions, have been built on the nuclear shell model, which is a framework analogous to the atomic shell model; however, no predictive nuclear model has been found to be complete. An accurate lifetime measurement for an excited nuclear state determines the off-diagonal nuclear matrix element, and thus study the nuclear wavefunctions with well-defined electromagnetic multipole operators. Essentially, this allows one to investigate qualities of predictive nuclear models, or develop more accurate models in the future.

A low-energy Coulomb excitation experiment was performed to measure electromagnetic transition rates of excited states in 36Ar at TRIUMF, Canada's particle accelerator. An 36Ar beam was impinged upon a 12C target with 197Au backing. This target was designed to use the Doppler-shift attenuation method (DSAM), which is a lifetime extraction method. To detect the gamma-rays and particles emitted during the experiment, the TRIUMF-ISAC Gamma-Ray Escape Suppressed Spectrometer (TIGRESS) and 丁香园AV's TIGRESS Integrated Plunger (TIP) device were used. The obtained gamma-ray and particle spectra are compared with simulated spectra generated by GEANT4 framework. Statistical analysis are then applied to extract the best-fit lifetime.

This presentation includes the process of lifetime measurement for 2+ to 0+ transition in 36Ar. Future analysis will explore the lifetime measurements of excited 37Ar, which was also produced in the experiment.

Development of Calibration Systems for the Pacific Ocean Neutrino Experiment

The Pacific Ocean Neutrino Experiment (P-ONE) is a cubic-kilometre scale neutrino telescope to be deployed deep in the northern Pacific Ocean off the coast of Vancouver Island. P-ONE aims to measure high-energy astrophysical neutrinos to learn about their production mechanism and sources. The detector will be composed of an array of kilometre tall mooring lines instrumented with P-ONE Optical Modules (P-OMs) which detect Cherenkov light from neutrino-induced secondary particles. To ensure accurate measurements, both the optical properties of ocean water and position of each module must be known to high precision. The ocean is a dynamic environment where both of these parameters constantly vary and so to achieve this goal, P-ONE includes a variety of calibration systems for both localized and ranged real time detector calibration. Included are acoustic receivers and emitters for spatial trilateration and small fast light flashers integrated into each P-OM. Furthermore, some P-OM modules in the detector will be replaced with P-ONE CALibration (P-CAL) modules which contain a larger well calibrated nanosecond flasher along with some detection elements of the P-OM. This poster highlights the development, simulations, and lab measurements of these P-ONE calibration systems.

Optimal information encoding enables net work extraction from a partially observable Szilard engine

In the classical Szilard engine, a Maxwell demon makes perfect measurements, and all stored information leads to work extraction. However, a real system may produce ambiguous observations. For example, a crooked divider in a Szilard engine could make it difficult to infer which side the particle is on. We have experimentally realized optimally encoded measurements on a partially observable Szilard engine whose divider shape creates an ambiguous region in the middle. The experiment uses feedback optical tweezers and a colloidal particle in water. A deterministic 2-state memory, encoded as a double-well potential, leads to less work than a classical Szilard engine. We can offset the operational costs of the memory medium by using the work medium at a higher temperature than the memory. Adding a memory state (triple-well potential) to store the uncertain observations increases operational costs but also increases work extraction above a critical temperature for a given size of the ambiguous region. Surprisingly, a probabilistic memory encoding can lead to greater work extraction than a deterministic encoding.

Using Molecular Dynamics Simulations to Study the Morphology of Benzimidazolium and Imidazolium Anion Exchange Membranes

Finding suitable alternatives to unsustainable energy sources is a pressing matter considering the challenge of climate change. Hydrogen fuel cell technologies are a promising option due to their high efficiencies and energy densities. However, the traditional implementations of fuel cells have been plagued by scalability issues due to reliance on fluorine-based materials and to high costs of noble metals such as platinum. Hydrocarbon-based anion-exchange membranes (AEMs) are being developed to address these issues. We have been studying several AEM candidates using both computational and experimental techniques with a focus on ionomers, where the charge is along the polymer backbone. In this work we compare the structure and ion dynamics in membranes based on a series of benzimidazolium and imidazolium backbones using techniques such as molecular dynamics simulations and clustering analyses in order to improve our understanding of the differences between candidate membranes.

Discrete-Variable-Assisted Error Correction of Continuous-Variable Quantum Information

Quantum information can be encoded into a continuous wave function in harmonic oscillators. However, error correction in continuous-variable (CV) quantum information has remained challenging, with only a few available methods that are complex to implement. In this work, we introduce a new CV quantum error correction scheme that can be implemented with resources available in many quantum platforms, aiming to address the common error presented as random fluctuations in the position and momentum of the harmonic oscillator. By coupling the oscillator with a discrete-variable quantum state, we can extract information about the fluctuation and correct it. We demonstrate that with only one two-level ancilla (qubit), fluctuation can be suppressed up to 18%, and error correction can be arbitrarily improved by increasing the level of the ancilla.

Terahertz spectroscopy of the superconducting state of titanium nitride

We present terahertz time-domain spectroscopy measurements of titanium nitride as a function of temperature in the superconducting state. By employing a maximum-likelihood analysis method developed by our group, we demonstrate that the Mattis-Bardeen theory of disordered superconductivity can describe the complex frequency-dependent conductivity 饾湈"(饾憮) at each temperature with only one free parameter, the temperature dependent energy gap 螖(饾憞). Our results provide a quantitative test of Mattis-Bardeen theory and demonstrate the advantages of our maximum-likelihood analysis framework