Preparing Greenberger-Horne-Zeilinger Entangled Photon Fock States of Three Cavities Coupled by a Superconducting Flux Qutrit

We propose a way to prepare Greenberger-Horne-Zeilinger (GHZ) entangled photon Fock states of three cavities, by using a superconducting flux qutrit coupled to the cavities. This proposal does not require the use of classical microwave pulses and measurement during the entire operation. Thus, the operation is greatly simplified and the circuit engineering complexity and cost is much reduced. The proposal is quite general and can be applied to generate three-cavity GHZ entangled photon Fock states when the three cavities are coupled by a different three-level physical system such as a superconducting charge qutrit, a transmon qutrit, or a quantum dot.