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Sunday, January 30, 2022

Quantum Computers Could Crack Bitcoin. Here’s What It Would Take [SingularityHub, January 2022]

Title:
Quantum Computers Could Crack Bitcoin. Here’s What It Would Take
 
Author:
Edd Gent
 
Published:
SingularityHub, 30 January 2022
 
From the article:
Quantum computers could cause unprecedented disruption in both good and bad ways, from cracking the encryption that secures our data to solving some of chemistry’s most intractable puzzles. New research has given us more clarity about when that might happen. 

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Title:
The impact of hardware specifications on reaching quantum advantage in the fault tolerant regime

Authors:
Mark Webber, Vincent Elfving, Sebastian Weidt & Winfried K. Hensinger

Published:
AVS Quantum Science, 25 January 2022

Abstract:
We investigate how hardware specifications can impact the final run time and the required number of physical qubits to achieve a quantum advantage in the fault tolerant regime. Within a particular time frame, both the code cycle time and the number of achievable physical qubits may vary by orders of magnitude between different quantum hardware designs. We start with logical resource requirements corresponding to a quantum advantage for a particular chemistry application, simulating the FeMo-co molecule, and explore to what extent slower code cycle times can be mitigated by using additional qubits. We show that in certain situations, architectures with considerably slower code cycle times will still be able to reach desirable run times, provided enough physical qubits are available. We utilize various space and time optimization strategies that have been previously considered within the field of error-correcting surface codes. In particular, we compare two distinct methods of parallelization: Game of Surface Code's Units and AutoCCZ factories. Finally, we calculate the number of physical qubits required to break the 256-bit elliptic curve encryption of keys in the Bitcoin network within the small available time frame in which it would actually pose a threat to do so. It would require 317 × 106 physical qubits to break the encryption within one hour using the surface code, a code cycle time of 1 μs, a reaction time of 10 μs, and a physical gate error of 10−3. To instead break the encryption within one day, it would require 13 × 106 physical qubits.