Quantum Measurements with Quasiprobabilities

Invited talk for the QuiDiQua conference, 2023/11/10

How to communicate a QR code without a trace

Invited talk for the 30th Anniversary Conference on Interaction Free Measurement, Chapman University, 2023/04/27

Spin Angular Momentum in Acoustic Field Theory

ADVANCES IN OPERATOR THEORY WITH APPLICATIONS TO MATHEMATICAL PHYSICS, November 14, 2022. Using an acoustic analog of Minkowski geometry, we construct a Lagrangian representation of acoustic field theory that accounts for the recently measured nonzero spin-angular-momentum density of sound fields in fluids or gases. While the traditional acoustic Lagrangian representation of the measured pressure and velocity fields using a dynamical scalar potential is unable to describe the vector character of the spin, we show that the pressure-velocity 4-vector additionally admits a dynamical bivector potential that correctly accounts for the spin. In the equilibrium frame this bivector potential reduces to a displacement field with amplitude equal to the scalar potential, such that its gauge freedom is equivalent to the arbitrary choice of displacement origin. The two potentials combine into an even-graded spinor potential with dynamics that recover the observed local radiation forces and torques on small probe particles, as well as the correct canonically conserved momentum and spin densities as proper Noether currents. This twin-potential construction for acoustics closely mirrors a formulation of vacuum electromagnetism that combines both electric- and magnetic-potential representations into a manifestly dual-symmetric odd-graded potential.

Quantum Contextuality as Erasure

New Directions in Function Theory: From Complex to Hypercomplex to Non-commutative, November 21-26 2019, Chapman University, ORANGE, CA Abstract: We formulate multiparticle quantum mechanics as an algebraic quotient space constructed from redundant copies of spacetime. We demonstrate that the needed equivalence relation erases geometric distinctions, leading to entanglement correlations and other context-dependent measurement effects. This quotient construction has close connections to resource theories derived from symmetry groups, which we also review.

When Less is More

SACNAS 2019 Slides

Numpy and Pandas Overview

An introduction to the Python libraries numpy and pandas for numeric and data-oriented computing.

Weak values : From superoscillations to mean-field estimates

Invited talk for the Superoscillation conference in Cetraro, Italy, 6/15/2019

Strengthening weak measurements for qubit multitime correlators

Chapman University, PIMan 2019 Workshop, 3/20/2019

Dual-symmetric Electromagnetism, a Clifford-algebraic approach

Advances in Operator Theory with Applications to Mathematical Physics November 12-16 2018, Chapman University, ORANGE, CA Abstract: We show how to use Minkowski spacetime Clifford algebra to efficiently describe electromagnetism. The electric and magnetic fields are combined into a single complex and frame-independent bivector field, which generalizes the Riemann-Silberstein complex vector that has recently resurfaced in studies of the single photon wavefunction. The complex structure of spacetime also underpins the emergence of electromagnetic waves, circular polarizations, the normal variables for canonical quantization, the distinction between electric and magnetic charge, complex spinor representations of Lorentz transformations, and the dual (electric-magnetic field exchange) symmetry that produces helicity conservation in vacuum fields. This latter symmetry manifests as an arbitrary global phase of the complex field, motivating the use of a complex vector potential, along with an associated transverse and gauge-invariant bivector potential, as well as complex (bivector and scalar) Hertz potentials.

Strengthening weak measurements for qubit tomography and multitime correlators

Chapman University, MPC Seminar 10/4/2018; RIKEN Invited Seminar 1/16/2019

Quantum Computing : State of Play

OC ACM Chapter Meeting, May 16, 2018

Watching Superconducting Qubits with Microwaves

QCMC2018, Baton Rouge LA, 3/13/2018 ; Keio University, 7/17/2018

Quantization from Clifford Algebra

APS March Meeting 2018

Weak Values in the Wild

Conference talk for the 30th Anniversary of the Weak Value at Chapman University, 3/1/2018

Continuous measurements of a superconducting qubit: from many-worlds to master equations

ICQF2017 : Patna, India

Exploring quantum mechanics with your laser pointer

Watching a quantum system: How to continuously measure a superconducting qubit

USC Physics Colloquium : September 11, 2017 ; Chapman MPC, September 27, 2017 ; UW Madison, October 26, 2017

What does a continuously monitored qubit readout really show?

For continuous measurements of a quantum observable it is widely recognized that the measurement output approximates the expectation value of the observable, hidden by additive white noise. Filtering the measurement readout can thus approximately uncover the dynamics of the expectation value, during a single realization. However, using information from the entire output history yields a different, smoothed, observable estimate. We derive the form of this smoothed estimate and show that the observed readout quantitatively tracks it with higher fidelity than the expectation value during a single realization, making it an objectively meaningful quantity. In the weak measurement limit this smoothed estimate approximates a weak value, with no need for additional postselection.

Probing Macro-Realism with Superconducting Quantum Bits

Wash U, st Louis 10/2016; RIKEN 7/2018

Python Objects Overview

An introduction to Python objects as a method for modular design in scientific computing.

IPython Overview

These slides offer a condensed description of the essentials of using IPython for professional interactive reports.

Git and GitHub Overview

These slides offer a condensed description of the essentials of using git and GitHub to manage an open-source code-base.

Vim Overview

These slides offer a condensed description of the essentials of using vim inside a bash shell.

Linux and Bash Overview

These slides offer a condensed description of the essentials of using linux with the bash shell, for help in reaching proficiency quickly.

CS 510 - Orientation

In this Chapman University course in the Data and Computational Sciences (CADS) graduate program, you will be introduced to a broad array of powerful and inter-operable tools for exploring and solving scientific problems in a computational setting.

Avoiding Loopholes with Hybrid Bell-Leggett-Garg Inequalities

Entanglement-Enhanced Weak Value Amplification

Experimental violation of a Hybrid Bell-Leggett-Garg inequality with weak measurements

Weak and Continuous Measurements with Superconducting Circuits

Delayed Choice Lorentz Rotations

An analysis of qubit evolution in terms of Lorentz transformations.