# John Lekner

**Emeritus Professor - Physics** School of Chemical and Physical Sciences

## Research interests

Optics, electromagnetism and quantum theory

Propagation, polarization and reflection of focused laser beams. Invariant properties of light beams. Energy, momentum and angular momentum of electromagnetic and acoustic pulses. Quantum many-body theory; fluid mechanics.

My current focus is on the theory of electromagnetic pulses, in relation to work on my second book (below).

## Newly published paper

Focal extent of scalar beams, J. Opt. 22, 045607 (9pp) (2020)

Comparison of electromagnetic beams, Optics Communications 458, 124844 (8pp) (2019)

Other publications.

## Published books

Theory of electromagnetic pulses. Morgan & Claypool Publishers (2018, 1st Edition)

This book presents the theory of electromagnetic pulses in a simple and physical way. All pulses discussed are exact solutions of the Maxwell equations, and have finite energy, momentum and angular momentum. The subject matter is restricted to free-space classical electrodynamics, but contact is made with quantum theory in proofs that causal pulses are equivalent to superpositions of photons.

Theory of Reflection: Reflection and Transmission of Electromagnetic, Particle and Acoustic Waves, Springer (2016, Second edition).

## Nature news item

Like attracts like? Nature: international weekly journal of science (23 May 2012)

## More information

View my publications.

View animations of particle wavepackets:

- A0 Motion of the free-particle Gaussian wavepacket through its focal region.
- B0 Motion of the free-particle Gaussian wavepacket through its focal region.
- A1 Motion of the non-reflecting wavepacket Φ1(x,t) through the potential region.
- B1 Motion of the wavepacket Φ1(x,t) through the potential region.
- C1 Comparison of the motion of the wavepackets Φ0(x,t) and Φ1(x,t).
- A2 Total reflection of a wavepacket by the potential ħ / mx
^{2}. - A3 Partial reflection of a wavepacket by the delta function repulsive potential.
- A4 Contraction and spreading of the Airy wavepacket in its zero-momentum frame.
- B4 Space curve of the Airy wavepacket in its zero-momentum frame.
- A5 Gaussian wavepacket in gravitational field.
- A6 Schrödinger packet for a particle in a harmonic oscillator potential.
- B6 Harmonic oscillator wavepacket: an animated space-curve.
- C6 Packet based on first excited state of harmonic oscillator.
- A7 Quantum bouncer on a spring.
- A8 Airy wavepacket in gravitational field.