Researchers Demonstrate 0.10 Concurrence Between 2 Transmon Qubits in Kraus-Cirac Entanglement Test
Updated
Updated · Quantum Zeitgeist · Jul 14
Researchers Demonstrate 0.10 Concurrence Between 2 Transmon Qubits in Kraus-Cirac Entanglement Test
1 articles · Updated · Quantum Zeitgeist · Jul 14
Summary
Two transmon qubits reached a stabilized entangled steady state with concurrence of 0.10 ± 0.01, marking the first experimental demonstration of the Kraus-Cirac hybrid entanglement scheme proposed more than 20 years ago.
A nondegenerate Josephson parametric converter generated a broadband two-mode squeezed microwave field that drove the qubits into entanglement through correlated photonic reservoirs rather than direct photon exchange.
The setup worked autonomously, without synchronized pulses or active control, with each qubit linked to the source by 50 centimeters of coaxial cable and the measured behavior matching theory.
The result helps bridge continuous-variable photonic entanglement and discrete-variable qubit processing, offering a route to scalable multiqubit networks and direct cryogenic certification of weak microwave-state entanglement.
On July 14, 2026, researchers achieved a major breakthrough by autonomously generating and stabilizing hybrid entanglement between two transmon qubits. Using a prototype dual-rail quantum network, they employed a Josephson parametric converter to create a broadband two-mode squeezed state of correlated microwave photons. These photons acted as a shared entanglement reservoir, which autonomously drove two spatially separated qubits into a steady-state entangled configuration. This experiment bridges the gap between continuous-variable (photonic) and discrete-variable (qubit) quantum systems, marking the first practical realization of a hybrid entanglement distribution scheme and paving the way for robust quantum networks.