[Cryptography] information, Shannon, and quantum mechanics

[Watson Ladd]

On Tue, Feb 24, 2015 at 6:59 AM, Henry Baker <hbaker1 at pipeline.com> wrote:
> At 04:59 PM 2/23/2015, John Denker wrote:
>>> We still don't know what a bit _weighs_;
>>
>>The short answer is zero.
>
> Bzzzt!
>
> If you had mentioned the word "Bekenstein", we might be able to have a conversation.

No, Denker is right. You can perform a reversible computation with
zero entropy gain. Even if you erase a bit, that might not cost
energy, but can cost entropy. See for example
http://rspa.royalsocietypublishing.org/content/royprsa/early/2011/01/07/rspa.2010.0577.full.pdf.

Sincerely,
Watson Ladd

>
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