Yesterday in #PHY531 #QuantumMechanics: A classical particle cannot transmit through a delta function barrier, but a quantum particle may tunnel through with probability that increases with the energy of the particle.

Yesterday in #PHY201 #GenPhys1: The work that a force does on a moving object equals the amount of the force along the motion, times the displacement. Forces that push with the movement do positive work, against do negative work, and perpendicular to do zero work.

Today in #PHY131 #QuantumForEveryone: The double slit experiment with electrons shows that matter has a wave nature, too. Video from iopscience.iop.org/article/10.108…. An electron microscope uses electrons, which have shorter wavelengths than light, to view small objects, even atoms!

🚨 Last chance to submit your poster for #QIP2026! 🗓️ Deadline: October 10, 2025 (AoE) 👉 Submission details: qip2026.lu.lv/submission/sub…

Today in #PHY531 #QuantumMechanics: For a delta-function well, a classical particle with E > 0 always transmits, but a quantum particle can reflect. It's like the opposite of tunneling. With E < 0, there is one bound state that decays exponentially from the well.

Had a great week at BIRS, where I led a working group on an open problem in quantum search algorithms, as well as presented research on Quantum Search and State Transfer with a Generalized Laplacian.

Today in #PHY531 #QuantumMechanics: For a finite square well, a classical particle with positive energy transmits with probability 1. But a quantum particle only transmits with certainty for particular energies, and more energy does not necessarily mean more transmission.

Today in #PHY201 #GenPhys1: The net work on an object changes its kinetic energy. This directly relates force (via work) and velocity (via kinetic energy). Before, we needed Newton's laws to go from force to acceleration, and then kinematics to go from acceleration to velocity.

Students in General Physics for the Life Sciences #PHY201 #GenPhys1 can be a tough crowd, but today, a student told me, "I no longer hate physics." While that doesn't mean they love physics, I'll take the win!

Today in #PHY131 #QuantumForEveryone: In atoms, electrons' waves takes shapes called orbitals, which are responsible for chemistry. A quantum particle can tunnel through a barrier, yielding in scanning tunneling microscopes, flash memory, and this year's Nobel Prize in Physics.

Yesterday in #PHY531 #QuantumMechanics: For a quantum particle in a box, the number of allowed energies increases as the box gets wider or deeper. In Dirac notation, we express column vectors as kets and their conjugate transposes as bras, and their inner products brackets.

Yesterday in #PHY201 #GenPhys1: The work done by a conservative force is path independent. It defines a scalar at all points from a reference point. The negative is potential energy. (Initial mechanical energy) + (work done by non-conservative forces) = (final mechanical energy).

Today in #PHY131 #QuantumForEveryone: Quantum particles can have intrinsic angular momentum, called spin, and act like little bar magnets. This yields fine and hyperfine energy levels for atomic clocks and astronomy, and also yields magnetic sensors and MRI machines.

Today in #PHY531 #QuantumMechanics: Generalizing of linear algebra to complex vector spaces and Hilbert space, including the norm, normalization, orthogonality, completeness, and Cauchy-Schwarz inequality.

New paper with Creighton University sophomore Jonas Duda and recent graduate Molly McLaughlin, BS'25 on "Quantum Search with a Generalized Laplacian." Paper: doi.org/10.1103/fsxq-t… Physical Review A Video: birs.ca/events/2025/5-… BIRS

Yesterday in #PHY531 #QuantumMechanics: A Hermitian (self-adjoint) operator equals its Hermitian conjugate (adjoint). It is an observable. Its eigenvectors are determinate states of the observable, whose measurement outcomes are the eigenvalues.

Yesterday in #PHY201 #GenPhys1: A net force applied for some time changes the momentum of the system. In an isolated system, momentum is conserved. We calculated how fast Fulton Reed's hockey puck must travel in The Mighty Ducks to knock a goalie into the goal.

Today in #PHY131 #QuantumForEveryone: Review of Part 1 of the course, which consists of seven units focusing on established quantum technologies. An exam on this is next!

Today in #PHY531 #QuantumMechanics: We derived the generalized uncertainty principle (pictured). If two observables commute, it is possible to find simultaneous determinate states (eigenfunctions) of both, which have guaranteed outcomes (eigenvalues) with zero spread.

Today in #PHY201 #GenPhys1: In a 1D elastic collision of two objects, relative velocity flips. In a ballistic pendulum, cons' of momentum is followed by cons' of energy. In a 2D collision, use components. Spreading an impulse over a longer time decreases the average force.