Quantum computers could theoretically break Bitcoin security encryptions.
There are more alarmist analysts than others; Most agree that the quantum risk is distant.
The Ionq technology company announced on June 9 an ambitious goal: to build by 2030 a quantum computer with 2 million physical cubits and 80,000 logical cubits (Qubitsin English). A day later, IBM, one of the historical pillars of global technology, presented its road map to develop the “first large -scale quantum computer and tolerant of failures” with 200 logical cubits by 2029.
Also, according to IBM statement, that quantum computer will lay the foundations for its future quantum Blue Jay, capable of executing one billion operations with 2,000 logical cubits on a horizon even without a defined date.
These advances, added to what is done by a group of the University of Oxford, although driven to favor science, the elaboration of drugs, to finance or security, promote a debate in the Bitcoin ecosystem: Can these machines represent a threat to network safety?
Expert estimates about quantum and bitcoin
The X user known as Borovik, a technology enthusiast, affirmed Last December, after the launch of the Google Willow quantum chip, which would be needed Between 13 million and 1.9 billion physical cubits to compromise bitcoin within a practical period ».
Along the same lines, but referring to the SHA-256 algorithm, the Bitcoin mining base, cryptootics Calculate that 317 million physical cubits are required to break it.
The relationship between physical and logical cubits is not fixed, but a standard commonly accepted considers that they are needed Between 100 and 1,000 physical cubits to build a logical cubitsdepending on the technology and the efficiency of error correction.
This distinction is crucial, since most analysts who evaluate the quantum threat for Bitcoin speak in terms of physical cubits, while IBM and Ionq The logical cubits stand out in their projectionswhich requires a conversion to compare both scenarios.
For his part, Adam Back, co -founder of Blockstream, approximated that “300 million physical cubits” would be necessary And a study by the University of Sussex calculated that 13 million physical cubits would be enough to decipher Bitcoin cryptography in one day. Others information They coincide with what is raised by Sussex.
However, Charles Edwards, founder of the financial firm Capriole, offered A more alarming perspective. In December, he said that “Only 2,500 logical cubits could be enough to break the SHA-256 algorithm in Bitcoin”refuting higher estimates from other experts.
Edwards added that “the correction of errors exponentially improves every year” and that, although the exact deadline is uncertain, “there is a serious risk of 50% for Bitcoin in 5 to 10 years.” For him, the urgency lies in acting today to prepare the network before this threat. In accordance with Edwards, scientist Anastasia Marchenkova also points to 2,500 logical cubits.
So, does Bitcoin’s security are in danger because of quantum?
To compare these estimates with IBM and Ionq ads, it is necessary to convert physical cubits to logical cubits.
Using the most optimistic conversion (100 physical cubits for 1 logical cubits), the 13 million physical cubits mentioned by Borovik and the University of Sussex would be equivalent to 130,000 logical cubits, while the 300 million back would translate into 3 million logical cubits.
These figures are significantly greater than the 200 logical cubits of IBM by 2029 or the 80,000 IONQ by 2030, so, according to these approaches, The danger would still be distant.
However, Edwards estimate of 2,500 logical cubits is much closer to what IBM plans to achieve in just four years, which suggests that the risk could materialize earlier than planned by other analysts.
The cryptography that supports Bitcoin, based on the algorithm ECDSA (Elliptical curve digital signature algorithm), protects private keys that guarantee the property of funds.
However, quantum computing, with its ability to solve complex mathematical problems at unattainable speeds for classic computers, could, in theory, decipher this encryption in the future.
Conveniently, Bitcoin’s ecosystem is taking measures to face quantum threat. For example, in April 2025 a Chilean developer proposed a Hard fork (hard bifurcation) for Implement addresses based on post-quantic cryptographyreplacing the ECDSA algorithm.
Ben Sigman, CEO of Bitcoin Libre, said that the BIP-360 improvement proposal would strengthen Bitcoin’s resistance to advances in quantum computing.
