For years, the idea of a quantum computer breaking Bitcoin sounded like a problem for the distant future. IonQ has now put a number on it: about 26 days.
The company modeled a future quantum computer with nearly 20,000 qubits that could try to break the security used to verify Bitcoin transactions.
A machine powerful enough to do that does not exist today, but the study gives a clearer idea of what an attack could require. The concern also extends beyond Bitcoin because similar security methods protect software, websites, and connected devices.
IonQ maps a quantum attack down to the hardware
IonQ said its researchers produced the first fully compiled, end-to-end resource estimate for running Shor’s algorithm against secp256k1. The calculation is based on its trapped-ion Walking Cat architecture and accounts for the algorithm, compiler, hardware layout, and error-correction layer rather than stopping at a high-level qubit estimate.
The model calls for 19,397 physical qubits and 1,457 logical qubits, with about 39 million logical Toffoli gates. The Quantum Insider reported that the estimated 25.7-day runtime applies to each attempt, an important distinction from saying Bitcoin could simply be broken on a fixed 26-day countdown.
Interesting Engineering also noted that the physical-qubit total includes the hardware needed to run the calculation with quantum error correction. That makes the estimate more demanding than simply assembling 20,000 raw qubits.
What eWeek found
IonQ modeled how long one attempt could take on a future fault-tolerant quantum computer with nearly 20,000 physical qubits. No quantum computer available today can carry out the attack described in the study.
A simpler way to read IonQ’s numbers is:
IonQ’s estimate | What it means for readers |
| 25.7 days | One modeled attempt to crack the mathematical problem behind a Bitcoin signature |
| 19,397 physical qubits | The size of the fault-tolerant quantum computer IonQ estimates would be needed |
| 1,457 logical qubits | The error-corrected computing power actually used to run the attack |
| 40.7% to 63.3% chance of success | A 26-day attempt would not necessarily succeed on the first try |
| Around 2028 on IonQ’s roadmap | IonQ expects to build systems approaching this scale, but this is not a deadline for Bitcoin becoming vulnerable |
The success probability is an important limitation. IonQ calculated a rigorous lower bound of 40.7% for a single attempt and estimated that it could reach about 63.3% under additional mathematical assumptions. So even on the machine described in the blueprint, “26 days” would not mean a guaranteed break after exactly 26 days.
IonQ also said systems with the relevant capabilities fit its hardware roadmap around 2028. That date should not be read as a prediction that Bitcoin will become vulnerable in 2028. Reaching a targeted qubit count is only one part of building a quantum computer capable of reliably performing a calculation of this scale.
Why the risk goes beyond Bitcoin
Bitcoin is the easiest example to recognize, but IonQ’s research points to a much wider security problem. The same family of elliptic-curve cryptography is used to prove that software, devices, websites, and other digital systems are really what they claim to be.
For example, digital signatures can help verify that a software update came from a trusted developer, that a device is authorized to connect to a network, or that a digital certificate belongs to the correct organization. A sufficiently capable quantum computer could eventually undermine some of those protections, not just cryptocurrency signatures.
IonQ specifically pointed to code signing, digital certificates, device identity, and long-lived roots of trust as areas that could face similar risks.
There is already a replacement path. NIST has standardized quantum-resistant digital-signature algorithms including ML-DSA and SLH-DSA and is urging organizations to begin moving away from cryptography that could eventually be vulnerable to quantum attacks.
Bitcoin is not in immediate danger, but IonQ’s study gives companies a reason to look at the security methods they still rely on today. If future quantum computers can break some of those protections, businesses will need to know which systems are affected and how easily they can be updated.
Also read: Singapore’s S$37 billion RIE2030 plan is pushing quantum computing closer to commercial use, with new funding aimed at turning research into real-world industry applications.