Superconducting Qubits Reveal How Light Emission Can Be Precisely Controlled

Botao Du of the Purdue University and colleagues have, for the first time, directly observed the microscopic decay dynamics of multiple superconducting qubits coupled to a microwave waveguide. Investigations of collective radiative decay previously relied on measurements of emitted radiation, obscuring the behaviour of the emitters themselves. Published on 13 May 2026, this work reveals collective decay regimes extending beyond the standard Dicke model. Strong interactions between qubits stabilise both superradiance and subradiance, phenomena relating to enhanced and suppressed collective emission. This observation provides a new experimental platform for exploring collective quantum effects and may aid the development of more stable quantum technologies.

Multiple quantum bits, or qubits, interact and lose energy when working together as a collective, offering a new understanding of complex quantum behaviours beyond existing theoretical models. Strong interactions between qubits stabilise both superradiance and subradiance, phenomena relating to enhanced and suppressed collective emission. This observation provides a new experimental platform for exploring collective quantum effects and may aid the development of more stable quantum technologies.

The first direct observation of how multiple superconducting qubits decay when linked by a microwave waveguide, a channel directing microwave signals between quantum components, has been achieved. Previously, understanding collective behaviour relied on measuring emitted radiation, obscuring what was happening within the qubits themselves. This research reveals regimes beyond the simplified Dicke model, where strong interactions between qubits stabilise both superradiance and subradiance, akin to a group of light bulbs that either shine much brighter or much dimmer than expected when switched on together, due to interference. This breakthrough establishes a new platform for exploring complex quantum effects and could pave the way for more robust quantum technologies.

Engineered qubit-waveguide coupling for observation of collective superradiant and subradiant

A superconducting qubit array, linked by a microwave waveguide, a pipe directing microwave signals, enabled detailed observation of qubit behaviour. The architecture not only provided control over qubit interference, but also allowed microscopic measurement of their collective dynamics, with each qubit individually monitored as the system evolved. Carefully engineered connections between qubits and the waveguide, with precisely tuned amplitude and phase, manipulated collective interference, creating and controlling superradiance and subradiance; these phenomena resemble a group of light bulbs either shining much brighter or much dimmer than expected due to interference.

Stabilised superradiance and subradiance via strong inter-qubit interactions in a superconducting

Superradiance and subradiance were stabilised for over 60 picoseconds, a duration previously unattainable in similar qubit arrays lacking strong inter-qubit interactions. This breakthrough surpasses the limitations of the standard Dicke model, which describes collective emission but fails to account for the stabilising effects of strong qubit-qubit interactions. Direct observation of microscopic decay dynamics tracked population evolution and tunable quantum correlations within multi-qubit states, revealing regimes where these interactions reshape decay pathways.

The new platform enables exploration of collective phenomena in many-body quantum optics and offers potential for strong quantum information processing via driven-dissipative approaches, providing a flexible means to investigate complex quantum behaviours. Site-resolved control and readout enabled direct observation of multi-qubit decay dynamics across various excitation levels, demonstrating that the system operates beyond the limitations of the standard Dicke model because strong qubit-qubit interactions reshape decay pathways. These interactions actively counteracted local dephasing, a common source of instability in quantum systems, and enabled the observation of spatially and spectrally structured many-body eigenstates; however, the 60 picosecond duration still falls short of the coherence times required for complex, sustained quantum computations.

Direct observation of multi-qubit decay dynamics reveals limitations in coherence timescales

Understanding how multiple quantum components interact and lose energy collectively has long been a goal for scientists building more stable quantum technologies. This work delivers a new platform for probing these interactions, moving beyond indirect measurements of emitted radiation to directly observe the microscopic decay of multi-qubit states. Despite this improvement, the observed stabilisation timescale of over 60 picoseconds remains a key limitation for practical quantum computation.

Researchers and Technology of China Wales have, for the first time, directly observed the decay of multiple superconducting qubits as they interact, utilising a specially designed qubit array and a microwave waveguide to mediate these interactions. This architecture allows precise control over qubit interference, revealing collective behaviour extending beyond the established Dicke model. Tracking population changes and quantum correlations, the team demonstrated stabilisation of both superradiance and subradiance, phenomena relating to enhanced and suppressed collective emission, for over 60 picoseconds, highlighting the impact of strong inter-qubit interactions on reshaping decay pathways.

Researchers directly observed the decay of multiple superconducting qubits interacting within an array, demonstrating control over collective behaviour beyond the Dicke model. This provides a new method for understanding how multiple quantum components lose energy together, moving beyond indirect measurements to observe microscopic decay dynamics. Strong interactions between the qubits stabilised superradiance and subradiance for over 60 picoseconds, counteracting local dephasing. The team intends to further explore collective phenomena in many-body quantum optics using this flexible platform.