193 research outputs found
Generation of GHZ entangled states of photons in multiple cavities via a superconducting qutrit or an atom through resonant interaction
We propose an efficient method to generate a GHZ entangled state of n photons
in n microwave cavities (or resonators) via resonant interaction to a single
superconducting qutrit. The deployment of a qutrit, instead of a qubit, as the
coupler enables us to use resonant interactions exclusively for all
qutrit-cavity and qutrit-pulse operations. This unique approach significantly
shortens the time of operation which is advantageous to reducing the adverse
effects of qutrit decoherence and cavity decay on fidelity of the protocol.
Furthermore, the protocol involves no measurement on either the state of qutrit
or cavity photons. We also show that the protocol can be generalized to other
systems by replacing the superconducting qutrit coupler with different types of
physical qutrit, such as an atom in the case of cavity QED, to accomplish the
same task.Comment: 11 pages, 5 figures, accepted by Phys. Rev.
Simple preparation of Bell and GHZ states using ultrastrong-coupling circuit QED
The ability to entangle quantum systems is crucial for many applications in
quantum technology, including quantum communication and quantum computing.
Here, we propose a new, simple, and versatile setup for deterministically
creating Bell and Greenberger-Horne-Zeilinger (GHZ) states between photons of
different frequencies in a two-step protocol. The setup consists of a quantum
bit (qubit) coupled ultrastrongly to three photonic resonator modes. The only
operations needed in our protocol are to put the qubit in a superposition
state, and then tune its frequency in and out of resonance with sums of the
resonator-mode frequencies. By choosing which frequency we tune the qubit to,
we select which entangled state we create. We show that our protocol can be
implemented with high fidelity using feasible experimental parameters in
state-of-the-art circuit quantum electrodynamics. One possible application of
our setup is as a node distributing entanglement in a quantum network.Comment: 15 pages, 7 figure
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