Circuit Quantum Electrodynamics (cQED) | Jaynes-Cummings Physics
Quick Technical Answer:
Circuit Quantum Electrodynamics (cQED) is the study of quantum optics realized with superconducting artificial atoms (transmons) coupled to microwave coplanar waveguide resonators governed by the Jaynes-Cummings Hamiltonian.
Formula / Unitary:
H = \hbar \omega_r \left(a^\dagger a + \frac{1}{2}\right) + \frac{\hbar \omega_a}{2} \sigma_z + \hbar g (a^\dagger \sigma_- + a \sigma_+)
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Frequently Asked Questions
What is the dispersive regime in cQED?
When the detuning |Δ| = |ω_a - ω_r| ≫ g, no real energy is exchanged between the qubit and the resonator, but the resonator frequency shifts conditionally by ±χ based on whether the qubit is in |0⟩ or |1⟩, enabling non-demolition readout.