The era of quantum computing is coming, is Bitcoin in danger?

     A team of UNSW engineers has brought the world a step closer to quantum computing by developing a device that allows two quantum units, or qubits, to communicate with each other. The device uses silicon to enable two qubits, or binary bits, to communicate with each other.

     In a quantum computer, qubits can be either 0 or 1, or even both at the same time. In theory, qubits that are both 0 and 1 at the same time allow computers to perform parallel calculations at very high speeds.

     The minimum requirement for performing quantum operations is to be able to perform operations between qubits. The dual-bit process can create logic gates with dual inputs and a single output. Andrew Dzurak, who led the research, explained: "Logical qubits are encoded by the spin of a single electron.

     The key problem is that in order for two electron spins to behave like a quantum unit, the two electrons need to be very close to each other, usually 20-40 nanometers, which requires a high degree of coupling and controllability. This is very difficult to achieve because the distance is too small. "

     Dzurak's team used earlier theoretical results to create two silicon-based quantum bits that can communicate with each other. The state of a qubit is determined by the spin of a single electron in an atom, making each transistor in a computer a unit cell.

     "Our key breakthrough was being able to address each qubit independently, just by controlling the voltage on the metal gate electrode to be higher than the voltage across the qubit," Dzurak explained. "This really simplifies single-qubit and two-qubit logic operations."

     Quantum computing still has a long way to go before it can reach higher levels and become more economical than current computers.

Quantum computing and Bitcoin

     What is the connection between quantum computing and Bitcoin? Will people's use of quantum computing methods cause Bitcoin to suffer? The answer is no, but quantum computing may cause some trouble for Bitcoin. It is estimated that the price of quantum computing will still be extremely expensive in the next decade, and it cannot be used to break the security system of Bitcoin to steal users' funds, so the user group is still very limited.

     The introduction of quantum computers will have two major effects on Bitcoin: the first is that the security of the elliptic curve cryptography used when signing transactions will need to be improved; the second thing is that the hashing itself will need to be upgraded.

     Quantum computers could compromise the security of elliptic curve cryptography because they can deduce that once a public key is known, it is possible to deduce the private key. Quantum computers can solve the discrete logarithm problem very efficiently.

     If an address is used only once, the hash of the transaction will mark the public key and protect the private key. Once the node knows the public key and tries to send other transaction requests from the same address without the user's knowledge, trouble will arise, but quantum computing has not yet developed, so it will not bother users.

     Quantum computing can also be used for hashing. Grover's algorithm is probably the first choice for finding collisions (two sequences hashing to the same value). Finding collisions is crucial if you want to replace blocks in blockchain technology, but quantum computers are not good at this. Currently, finding collisions to replace blocks is more expensive than it is effective.

     Quantum computing can be used to reduce the difficulty of hashing by about 1/5 (quantum computing reduces the number of units required to calculate because quantum bits can exist in the state of 0 and 1 at the same time). The biggest threat of quantum computing to security systems is that there may be a 51% attack probability for a period of time, but a 51% attack probability is enough to make people panic.

in conclusion

     Although quantum computing is one step closer to becoming a reality, it is still a long way from being realized. Quantum computing will pose a threat to virtual currencies and cryptographic systems, but if quantum computers are soon popularized around the world, it will not have any impact on the security of Bitcoin.

     Because we can see that quantum computing will be gradually introduced, there will be time to deal with the problems that Bitcoin will encounter when quantum computing occurs.