To function correctly, superconducting quantum computers must be cooled to temperatures approaching absolute zero, roughly -273 degrees Celsius. At such ultra-low temperatures, electrons in the circuit move without resistance, enabling the formation and stability of quantum states. Despite the advancements in cryogenic technology, the cooling systems themselves ironically introduce unwanted noise and energy fluctuations. This noise interferes with quantum coherence and degrades the information stored within qubits, threatening the reliability and scalability of quantum devices.

Recognizing this paradox, researchers at Chalmers University of Technology in Sweden have pioneered a radically new approach to refrigeration at the quantum scale. Their breakthrough device is a minimalistic quantum refrigerator that intriguingly utilizes noise itself as the engine of cooling. This innovative concept turns the conventional challenge of noise into an opportunity, enabling exquisite control over minute heat and energy flows within quantum circuits that conventional refrigeration methods cannot achieve.

At the core of this pioneering quantum refrigerator is an engineered superconducting artificial molecule. Unlike molecules formed from atoms, this artificial molecule is constructed from nanoscale superconducting circuits that imitate molecular properties. This unique system is coupled to two microwave channels acting as thermal reservoirs with distinct temperatures, one hot and one cold. The researchers manipulate thermal energy transfer between these reservoirs by injecting controlled microwave noise through auxiliary ports, effectively using fluctuating signals to drive heat flow and refrigeration.

This process exploits an elusive and theorized phenomenon called Brownian refrigeration, where random thermal fluctuations—previously considered a nuisance—can induce and power a directed cooling effect. The Chalmers team’s work stands as the closest experimental realization of this concept. By finely tuning the noise spectrum in a narrow band of microwave frequencies, they successfully orchestrate the energy exchange pathways, transforming random fluctuations into a resource for thermal management in superconducting systems.

Remarkably, the refrigerator operates with extraordinary sensitivity, detecting heat currents as feeble as attowatts—a scale so minuscule that warming a water droplet by one degree Celsius using this heat flow would take longer than the age of the universe. The precision in measuring and manipulating thermal currents at this scale represents a significant technical milestone, pushing the limits of control over quantum thermodynamics and fostering new possibilities for managing heat in quantum hardware.

Beyond refrigeration, this quantum device exhibits multi-modal functionality. By adjusting reservoir temperatures and noise intensity, it can transition between acting as a refrigeration unit, a heat engine, or an amplifier of thermal transport. This versatility holds profound implications for future quantum computing architectures, where local heat management is vital as quantum processors grow larger and more intricate. Heat generated during qubit operations must be carefully controlled to prevent decoherence and maintain computational integrity.

The ability to direct and harness thermal energy at such a nanoscale addresses a critical bottleneck in scaling quantum technologies. Classical cooling methods, though effective at macroscopic levels, lack the finesse to manage energy fluxes within individual quantum circuits. The Chalmers quantum refrigerator exemplifies a new paradigm where cooling mechanisms are integrated directly into the quantum device and driven by the system’s intrinsic noise properties, enabling unprecedented robustness and stability.

This breakthrough also provides fundamental insights into quantum thermodynamics—a field exploring how energy and information intersect at quantum scales. Understanding how to exploit noise, dissipation, and fluctuations not simply as obstacles but as functional resources reshapes our approach to quantum machine design. Devices like this refrigerator open the door toward engineered quantum heat engines and refrigerators that can operate autonomously and efficiently within quantum computing environments.

Fabricated at Chalmers’ Nanofabrication Laboratory, the artificial molecule that underpins this quantum refrigerator comprises superconducting circuits engineered to carefully mimic two coupled qubits. The design ingeniously enables the controlled injection of noise, with the illegal flow of heat contingent upon this noise driving the transfer between thermal reservoirs. Through extensive experimental calibration, the researchers confirmed the delicate balance required to achieve refrigeration powered purely by stochastic fluctuations.

Simon Sundelin, the doctoral student leading this project, highlights how understanding energy transport pathways at the quantum level is paramount for future device design. Their findings enable the anticipation and regulation of heat flows, paving the way for quantum devices in which thermal energy is not a destructive byproduct but a parameter that can be predictably manipulated to enhance device performance.

The study’s co-author, Aamir Ali, underlines the importance of this work for practical quantum technology. By removing heat at scales unreachable by conventional refrigeration, this method could make quantum processors more reliable and scalable. It enhances prospects for building larger, more complex quantum computers that retain coherence for longer operational cycles, accelerating progress toward practical quantum advantage.

Simone Gasparinetti, associate professor and senior author, points out that this work is a major step in realizing Brownian refrigeration, a concept long thought to be only theoretical. By converting random thermal fluctuations into a cooling force, their experiment not only solves a pressing engineering problem but also deepens our fundamental understanding of thermodynamic processes in quantum systems.

As the quantum revolution unfolds, innovations like the noise-powered quantum refrigerator underscore the importance of marrying fundamental physics with engineering ingenuity. By harnessing the very noise that threatens quantum coherence, researchers have revealed a new pathway toward stable, scalable, and efficient quantum machines—ushering in an era where quantum heat management becomes a controllable asset rather than an insurmountable hurdle.

Subject of Research: Not applicable

Article Title: Quantum refrigeration powered by noise in a superconducting circuit

News Publication Date: 26-Jan-2026

Web References: https://doi.org/10.1038/s41467-025-67751-z

References: Sundelin, S., Aamir, M. A., Kulkarni, V. M., Castillo-Moreno, C., & Gasparinetti, S. (2026). Quantum refrigeration powered by noise in a superconducting circuit. Nature Communications.

Image Credits: Chalmers University of Technology / Simon Sundelin

Keywords: Quantum computing, Quantum information, Qubits

Entanglement, the quintessential quantum phenomenon where particles become intrinsically linked regardless of distance, is foundational to quantum technologies. However, reliably certifying entanglement, especially over complex and extended networks susceptible to noise and device imperfections, has remained a formidable obstacle. Traditional verification methods often presume perfect measurement devices or require trust in the measurement settings, assumptions that can be exploited or fail in real-world implementations. By sidestepping these constraints, the newly demonstrated scheme marks a pivotal advancement toward practical and secure quantum networking.

At the core of this innovation lies the concept of a measurement-device-independent entanglement witness (MDI-EW), which, until now, primarily focused on discrete variable systems involving qubits. The researchers have extended the MDI paradigm to continuous variable systems, which use quantum properties such as the amplitude and phase quadratures of light, offering advantages in terms of measurement efficiency and compatibility with existing optical communication infrastructure. This transition to continuous variables significantly broadens the applicability of device-independent verification methods across quantum platforms.

The methodology involves leveraging an entanglement swapping procedure, mediated by an untrusted central node performing Bell state measurements, thus rendering the verification process independent of the measurement apparatus’s trustworthiness. Crucially, this approach facilitates entanglement witnessing even when the measurement devices are potentially compromised or uncharacterized. Unlike conventional methods dependent on precise calibration and control of measurement settings, this device-independent scheme enhances security by nullifying loopholes stemming from device vulnerabilities.

Implementing this protocol experimentally, the researchers utilized highly squeezed optical states to generate continuous variable entangled pairs, linking them across a network architecture. Their results demonstrated successful entanglement witnessing under realistic noise conditions, with high fidelity and resilience against typical losses encountered in fiber-optic channels. The scheme’s sensitivity to practical imperfections underscores its feasibility for deployment in current and near-future quantum networks.

Furthermore, by enabling real-time verification of entanglement that does not presuppose device trust, this technique fosters greater confidence in quantum key distribution (QKD) protocols and distributed quantum computation. It supports the validation of secure quantum correlations essential for cryptographic applications, where adversarial tampering with measurement devices could otherwise compromise security. Hence, this approach lays the groundwork for tamper-proof quantum communication infrastructures.

Of particular note is the scalability inherent in the measurement-device-independent continuous variable method. Because continuous variable systems naturally integrate with standard telecommunication components such as fiber optics and homodyne detectors, scaling to larger quantum networks becomes more practicable. This contrasts with discrete variable systems that often require delicate single-photon detectors, which can be bulky and less adaptable. Thus, this research offers a pathway to expansive quantum internet architectures.

The theoretical framework underpinning this work intricately combines principles from quantum optics, information theory, and cryptography. The researchers devised entanglement witnesses tailored to continuous variables that are robust against detector efficiency fluctuations and excess noise. These innovations pave the way for a versatile toolkit applicable beyond communication, extending to quantum sensing and metrology, where verifying genuine quantum correlations is pivotal for enhanced precision.

This breakthrough also addresses a vital concern in the community regarding standardization and certification of quantum devices. As quantum technologies edge closer to commercialization, establishing universally accepted benchmarks for entanglement verification becomes critical. By eliminating the dependency on trusted measurement devices, the proposed protocol potentially sets a new standard for device-independent verification, contributing to more transparent and trustworthy quantum device certification practices.

Moreover, the researchers’ demonstration includes comprehensive error analysis and optimization strategies, highlighting the robustness of their protocol against fluctuations in quantum state preparation and channel noise. These considerations are essential for transitioning from laboratory demonstrations to real-world applications where environmental instability and technological imperfections are unavoidable. Their framework ensures that entanglement certification remains reliable despite such challenges.

Looking ahead, this work opens several avenues for further exploration. Integrating the measurement-device-independent continuous variable entanglement witness with quantum repeaters could extend the range of secure quantum communication far beyond today’s limits. Additionally, its application in hybrid quantum networks combining discrete and continuous variables could exploit the strengths of both modalities, pushing the boundaries of quantum technology integration.

The convergence of these techniques heralds a new era in quantum information science, where secure and scalable quantum networks can be verified reliably even under adversarial conditions. This robustness is critical, not only for secure communication but also for distributed quantum computing, where verifying entanglement across network nodes ensures the integrity and performance of complex quantum algorithms running on spatially separated systems.

In summary, the introduction of a measurement-device-independent continuous variable entanglement witness represents a paradigm shift in quantum network verification. By leveraging continuous variable entanglement and detaching the verification process from trusted measurement assumptions, the research team has surmounted previous limitations, bringing us closer to building robust, scalable, and secure quantum networks. This milestone not only solidifies the theoretical foundations but also significantly advances practical implementations of quantum communication technologies.

As quantum networks advance toward ubiquitous deployment, such innovations are poised to underpin future quantum internet architectures that can securely interconnect quantum processors and sensors worldwide. The seamless integration with existing optical technologies and the resilience against device tampering reinforce the real-world readiness of this approach. Consequently, the quantum information community eagerly anticipates further developments and experimental validations building on this foundational work.

The methodology and results detailed in this study contribute vital insights and tools for navigating the precarious landscape of quantum security. With quantum technologies becoming increasingly sophisticated and widespread, ensuring robust verification protocols immune to device manipulation is indispensable. This work exemplifies scientific ingenuity addressing one of the most pressing challenges in the field and represents a significant leap toward practical, trustworthy quantum communication systems destined to transform computing, cryptography, and beyond.

Subject of Research: Measurement-device-independent continuous variable entanglement witnessing in quantum networks.

Article Title: Measurement-device-independent continuous variable entanglement witness in a quantum network.

Article References:
Fu, J., Wang, X., Liu, S. et al. Measurement-device-independent continuous variable entanglement witness in a quantum network. Light Sci Appl 14, 376 (2025). https://doi.org/10.1038/s41377-025-02039-x

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41377-025-02039-x