Quantum researchers have demonstrated a striking way to create and preserve entanglement by using the very process normally blamed for destroying it: dissipation. In a new experiment, superconducting qubits were driven into an entangled steady state through carefully engineered interactions with their environment, showing that energy loss and information leakage can become tools rather than obstacles for quantum technology.
The work, carried out by physicists at the University of Illinois Urbana-Champaign and the University of Chicago, realizes a theoretical proposal for generating entanglement in an externally driven quantum system. The researchers used two superconducting qubits connected by a unidirectional waveguide, a device that allows electromagnetic signals to travel from one qubit toward the other in a controlled direction. By combining this cascaded architecture with a technique known as synthetic squeezing, they were able to stabilize high-quality entanglement despite the imperfections present in a real laboratory system.
Entanglement occurs when two quantum objects share correlations that cannot be explained by classical physics. Measuring one object can reveal information about the other, even when they are physically separated. These correlations are essential for quantum computing, quantum communication and quantum sensing, but they are also extremely fragile. Interactions with the surrounding environment typically cause decoherence, rapidly erasing the delicate quantum relationships that make entanglement useful.
Conventional approaches usually create entanglement through a sequence of operations and then attempt to distribute the entangled particles or quantum states to separate locations. That transport stage is particularly vulnerable because noise, loss and uncontrolled interactions can degrade the quantum state. The new approach seeks to eliminate the need to move fragile quantum information. Instead, the qubits remain in place and continuously exchange signals, allowing entanglement to emerge as the stable outcome of their interaction with a driven and dissipative environment.
The key idea is based on cascaded quantum systems. In such a system, quantum objects continuously absorb and emit light or microwave photons. Some of that radiation escapes into the environment, creating dissipation. When an external drive is introduced with the correct phase, amplitude and direction, it can balance the dissipated field. The combined system then evolves toward a nonequilibrium steady state rather than simply losing its quantum properties. If the interactions are engineered correctly, that steady state contains entanglement between the separated qubits.
“This idea has attracted theoretical attention for a long time because it runs counter to our experience with quantum entanglement,” said Aashish Clerk, a professor of molecular engineering at the University of Chicago’s Pritzker School of Molecular Engineering. Rather than preparing entanglement once and watching it decay, he explained, the system naturally relaxes toward a state in which entanglement is continuously maintained. The researchers compare the effect to a refrigerator that uses an ongoing energy flow to preserve a desired condition, except that here the protected resource is quantum correlation rather than low temperature.
In idealized theoretical models, cascaded systems can generate strong steady-state entanglement. Real hardware, however, introduces unwanted loss, imperfect components and additional noise channels. These effects normally weaken the correlations and can prevent the system from reaching the predicted performance. Synthetic squeezing addresses this problem by modifying the effective quantum environment seen by the qubits. Through carefully selected drive settings, the researchers reproduce key features of an ideal squeezed reservoir without requiring a physically perfect source of squeezed radiation.
Squeezing is a distinctly quantum process that reduces uncertainty in one property of a field while increasing uncertainty in another. In the experiment, synthetic squeezing does not simply amplify the qubits’ interaction; it reshapes the noise and fluctuations entering the system. This allows the researchers to compensate for imperfections and tune the qubits toward an entangled steady state. Because the qubits are superconducting circuits, their quantum behavior can be controlled using microwave pulses, while the waveguide provides the directional channel needed for the cascaded interaction.
The experiment represents an important step toward quantum networks in which separated processors can share entanglement without transmitting delicate quantum states through long, noisy channels. The researchers are now exploring how the method can be extended from two qubits to larger systems. One possible application is entanglement distillation, a process in which many weakly entangled pairs are combined to produce a smaller number of pairs with stronger correlations. If such protocols can be integrated with the new architecture, the system could eventually support more demanding quantum operations and help connect remote quantum computers.
The researchers emphasize that the technique is not yet a complete quantum networking solution. The entanglement achieved remains below the theoretical maximum, and future work must determine which computational and communication protocols can benefit most from autonomous stabilization. Nevertheless, the result challenges a central assumption in quantum engineering: that environmental coupling is always destructive. By controlling the flow of energy, photons and information through a quantum system, dissipation can instead become the mechanism that repeatedly restores and protects entanglement.
Subject of Research: Dissipation-enabled generation and stabilization of entanglement between superconducting qubits in a cascaded quantum network
Article Title: Autonomous Stabilization of Remote Entanglement in a Cascaded Quantum Network
News Publication Date: 13-Jul-2026
Web References: Physical Review X: https://journals.aps.org/prx/abstract/10.1103/z6zz-vw5q ; Physics viewpoint: https://physics.aps.org/articles/v19/91
References: DOI: 10.1103/z6zz-vw5q
Image Credits: Wolfgang Pfaff
Keywords
Quantum entanglement, superconducting qubits, quantum networks, cascaded quantum systems, synthetic squeezing, dissipation, quantum computing, decoherence, quantum communication, quantum physics
