No quantum computer factored a 2048-bit RSA key. But Qrisp 0.8 compiled the full billion-gate circuit — the first gate-level Shor assembly at encryption-breaking scale, producing concrete qubit budgets the field has never had.
image from grok
Qrisp 0.8 has produced the first concrete gate-by-gate compilation of Shor's algorithm targeting 2048-bit RSA, generating T-gate counts and qubit budgets at ~10^9 gates per second—this is a compilation milestone, not a running one, since current quantum hardware lacks the error-corrected logical qubits and gate fidelity needed to execute the estimated billion-gate circuit. The compilation provides concrete circuit-level grounding for Craig Gidney's 2025 revised estimates showing RSA-2048 could be broken in under one week using fewer than one million noisy physical qubits, down dramatically from his 2019 estimate of 20 million qubits.
For the first time, a quantum computer has been programmed to factor a 2048-bit RSA key at the gate level: the physical circuit operations that would eventually break encryption. No actual factoring happened. No quantum hardware factored anything. But the compilation is real, and the numbers it produced are more concrete than anything the field has seen before.
The distinction between compiling and running matters enormously here. A quantum circuit is a sequence of gates applied to qubits. Writing down the gates is not the same as running them. Current quantum computers can execute hundreds or thousands of gates before noise degrades the computation into uselessness. Factoring a 2048-bit RSA integer requires roughly a billion gates on error-corrected logical qubits. Today's machines lack both the error correction and the qubit counts to attempt it. Qrisp 0.8 wrote down what that billion-gate circuit would look like, and how many physical qubits it would consume.
The numbers are striking. The compilation generates T-gate counts and qubit budgets in seconds at rates on the order of 10^9 gates per second, according to the release notes. That is a throughput figure for the compilation software, not the quantum hardware. The compiler is fast. The resulting circuit is a target. Hitting it requires a quantum computer with enough low-error qubits to run billions of gates without accumulating enough noise to corrupt the answer.
Previous resource estimates for breaking RSA-2048 relied on symbolic extrapolation or theoretical models. Qrisp 0.8 produced a concrete gate-by-gate assembly and an exact qubit budget. Craig Gidney, a quantum algorithms researcher at Google Quantum AI, published revised estimates in 2025 showing that 2048-bit RSA could be factored in under one week using fewer than one million noisy physical qubits, down from the 20 million qubits estimated in his 2019 work, according to his arXiv paper. Qrisp 0.8's compilation provides the circuit-level grounding those estimates were extrapolating from.
The technical leap in 0.8 comes from three additions working together. A new BigInteger type handles arbitrarily large integers during compilation by representing them as fixed-width little-endian base-2^32 words. This was necessary because the underlying Jax framework caps integers at 64 bits and cannot natively represent the multi-thousand-bit numbers in an RSA key. A Generalized Quantum Signal Processing module, called GQSP, implements the full hierarchy of Quantum Signal Processing techniques, a family of algorithms that underlies efficient Hamiltonian simulation and operator decomposition. A BlockEncoding class provides a NumPy-like interface for non-unitary matrix operations, which are essential for the modular arithmetic at the core of Shor's algorithm but are notoriously difficult to express in quantum circuits without blowing up resource requirements.
The Montgomery multiplication pipeline was reimplemented for Jasp tracing using the Gidney adder, enabling the compiler to track resource costs through the full circuit rather than stopping at high-level abstractions.
Qrisp is an open-source project at the Eclipse Foundation, primarily developed by Fraunhofer FOKUS and funded by Germany's Federal Ministry for Economic Affairs and Climate Protection and the European Union. IQM contributed the use case and hardware requirements that shaped the compilation targets.
What does this actually mean? The compilation produced engineering targets: how many T-gates, how many logical qubits, how the circuit would be assembled. Those targets are now on the table for hardware teams to assess. Whether current or near-term quantum computers can meet them is a separate question, and the answer today is no. IBM's Heron and Google's Willow are single-chip systems with a few hundred to a few thousand physical qubits operating with error rates around 0.1 to 0.3 percent per two-qubit gate. A fault-tolerant quantum computer capable of running Shor's algorithm at 2048-bit scale would require millions of physical qubits per logical qubit, with error rates orders of magnitude below current hardware.
The compilation is genuine progress. It moves the question from whether Shor's algorithm is theoretically feasible at RSA-2048 scale to what it actually takes, in gates and qubits, to run it. That is a meaningful shift. But the timeline for hardware that can execute this circuit remains long, depending on which optimistic roadmap you consult. The gap between compiling a circuit and running it is where quantum computing's hardest problems live.
What's worth watching is whether the Qrisp team's circuit descriptions get picked up by hardware teams at IQM, IBM, and elsewhere as concrete benchmarking targets, and whether Gidney's 2025 resource estimates get revised again as more detailed circuit data becomes available.
Story entered the newsroom
Assigned to reporter
Research completed — 4 sources registered. Qrisp 0.8 (Eclipse Foundation, Fraunhofer FOKUS) achieved first full gate-level compilation of Shor algorithm at 2048-bit RSA key sizes. Key technical
Draft (734 words)
Approved for publication
Published (734 words)
Get the best frontier systems analysis delivered weekly. No spam, no fluff.
Quantum Computing · 1d ago · 3 min read
Quantum Computing · 1d ago · 2 min read
