Rutgers and IBM report real-time feedback control across 100 qubits
Researchers from Rutgers, IBM and collaborators used a 156-qubit Heron chip to demonstrate repeated measurement and reset across up to 100 qubits.
Researchers from Rutgers, IBM and several partner institutions say they have demonstrated real-time quantum feedback across as many as 100 qubits, using repeated measurements and resets while a processor continued running. According to the announcement, the work was carried out on a 156-qubit IBM Quantum Heron processor and is described in a study published in Nature Physics. The result addresses a core requirement for fault-tolerant quantum computing: the ability to monitor parts of a system and intervene repeatedly without stopping the computation.
What was announced
The team says it used a connected chain of up to 100 qubits on IBM’s Heron hardware to test whether a quantum processor could alternate between two behaviors in real time: scrambling information across neighboring qubits and measuring then resetting individual qubits to suppress that scrambling.
In total, the experiment involved nearly 5,000 two-qubit operations and nearly 5,000 measurements and resets, according to the report. The researchers describe it as the largest successful demonstration so far of this type of feedback-based control.
Rutgers professor Jedediah Pixley, one of the senior authors, said the field will need to perform such checks and corrections many times during a computation to reach fault tolerance. IBM senior author Maika Takita said the challenge was to repeat measurements while the rest of the processor kept operating, rather than pausing the system.
The technical details
The experiment set up a competition between two processes. One process spread information among neighboring qubits, creating increasingly chaotic dynamics. The other process measured selected qubits and reset them, pushing the system toward an ordered state chosen by the researchers.
By varying how often each process occurred, the team observed a threshold behavior. When scrambling happened more than half the time, the system remained chaotic. When checking and resetting dominated, the system moved into a controllable ordered regime. Near an even balance, a small shift in the rate of the two processes changed the system abruptly.
According to the researchers, that sharp change matches a phase-transition picture: the quantum system switches collectively from chaos to control. Co-first author Haining Pan said the transition became more sharply defined as the team studied larger systems, and that the experimental data matched theoretical expectations.
The report also notes why the result matters for error correction. Quantum information cannot simply be copied, and measurement can disturb the state being computed on. A practical fault-tolerant machine therefore has to detect and correct errors repeatedly while preserving the encoded information.
Why it matters
The announcement frames the result as both a physics demonstration and a systems-engineering milestone. On the physics side, it supports a theoretical prediction that repeated interventions can drive a transition from uncontrolled quantum dynamics into an ordered, controllable regime. On the hardware side, it shows present-day superconducting hardware coordinating quantum gates, measurements and resets thousands of times across a large device.
That does not mean fault-tolerant quantum computing has been achieved. The report explicitly notes that no one has yet built a fault-tolerant quantum computer. But the ability to perform repeated measurement-and-reset cycles at scale is one of the operational ingredients such systems will require.
What to watch
The next question is how techniques like this translate into full error-correction protocols rather than controlled physics experiments. The study suggests IBM’s dynamic-circuit capabilities can sustain long sequences of interleaved operations on large qubit subsets, which is relevant for future logical-qubit demonstrations.
The collaboration included researchers from Rutgers, IBM, the City College of New York, the CUNY Graduate Center, Iowa State University, Ames National Laboratory, Pennsylvania State University and Louisiana State University. As reported in the announcement, the processor allowed the team to study systems much larger than the roughly two dozen qubits they could simulate on conventional computers.
Sources
Facts on this page come from the sources below, retrieved by DesignQuantum.
- Rutgers And IBM Demonstrate Real-Time Control Across 100 Qubits thequantuminsider.com