• In the article "Engage the antimatter drive", the words "charged particles" were mistakenly replaced with "gamma rays" (8 September, p 62). Unlike the former, the latter cannot be focused with magnets, and they travel at the speed of light.
• In trying to explain how encryption could be protected against being cracked by quantum computers, we wrote "The power of Shor's algorithm lies in its potential to use quantum processes to factorise large prime numbers" (15 September, p 30). That should of course have read "...to factorise encryption keys that are products of large prime numbers".
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