λEvanescent fields and near-field optics

Physical intuition

Evanescent waves carry subwavelength structure but decay away from an interface. This is the starting point for understanding how nanoscale optical geometry changes the states or dynamics accessible to light and matter.

Deep dive: how the mechanism works

For transverse momentum exceeding the surrounding light-line, the longitudinal wavevector becomes imaginary, producing exponentially decaying fields.

How the quantum phenomenon appears

A quantum dot close to a nanowire couples through its evanescent mode. To distinguish a genuinely quantum signal from a classical optical response, connect the device physics to a measurement such as photon correlations, interference visibility, energy-level structure or quantum-state tomography where appropriate.

Assumptions and limitations

Research and simulation exercise

Identify the tunable parameters, predict the observable from the stated model, and sweep one parameter while holding the others fixed. Compare against a simpler reference model, quantify loss and uncertainty, and state which observations would falsify the hypothesis.

Connect the ideas

See the chapter guide and further reading.