‘This new system will help you do more quantum computing, faster’: IBM says its Nighthawk r2 quantum processor marks a step change in compute capability

IBM is opening up its most complex quantum processor to researchers, claiming it can solve quantum advantage-level problems ten times faster than its current best model and with no loss in accuracy.

With 120 programmable qubits and a new high-speed qubit reset architecture, Nighthawk r2 is capable of executing over 100,000 circuits per second – 25 times the circuit throughput of IBM’s existing Quantum Heron fleet.

It's already demonstrated accurate observable estimation on circuits containing more than 7,500 gates, according to the firm.

The increase in speed comes thanks to Nighthawk r2's ability to address a longstanding bottleneck in quantum computing: reducing the time needed for qubits to 'reset' between computations.

Previous generations of IBM Quantum processors, including Heron, have managed the reset through a technique powered by dynamic circuits and called conditional reset.

The processor measures the state of a qubit and, if it's found to be in the |1⟩ state and applies a bit flip gate – specifically a π-pulse – that flips the qubit back to the ground state.

However, this technique is limited by the accuracy of measurement, and can't reset qubits that have leaked outside the computational state, meaning a delay of hundreds of microseconds between circuit executions.

Nighthawk r2, instead, uses a dissipative reset gadget, in which each programmable qubit is linked through a high-dynamic-range tunable coupler to a cold environment that draws it back to its ground state on demand.

Activating that coupler pulls a qubit’s effective T1 – the measure of how long it holds its energy – from a median of about 200 microseconds down to roughly 25 nanoseconds, enabling significantly faster high-quality reset.

This active qubit reset leaves neighboring qubits undisturbed while reducing idle time between circuit runs to as little as a single microsecond.

IBM hails Nighthawk compute gains

In practice, IBM said these gains are most noticeable in the large-scale, repetitive workloads that are common in the research community.

"Nighthawk r2’s improvements in speed and quality are already enabling exciting demonstrations of its quantum computational capability," said the firm.

"For example, following recent demonstrations of quantum advantage through trusted quantum computation, researchers used Nighthawk r2 to perform the doped Clifford sampling advantage experiments originally developed in a collaboration between UChicago and IBM."

IBM also cited other advantages of the new processor, claiming it maintains the scale of its r1 predecessor while delivering targeted improvements in quality.

Because the new high-speed reset capability actively cools the qubit to its ground state, it cuts initialization error across the device by about 25 times, making for more accurate results.

At the same time, it keeps up with the gate fidelity of Heron, even while operating at much higher speeds, and performs individual qubit reset without degrading the performance of the qubit’s neighbors.

"Whether you’re scaling application research, exploring the power of dynamic circuits, or advancing the latest quantum error correction research, this new system will help you do more quantum computing, faster," promised IBM.

"Ultimately, the most important thing about a quantum computer isn’t the number of qubits or components; it’s the amount of useful computation the system can deliver."

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