# Questions tagged [reversible-computing]

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### Is this statistical group summation unambiguously reversible?

Given an (unordered) set of 2-tuples (X) of natural numbers (I'm using SQL here for easy reproducibility, and because I don't know better): ...
23 views

### Two variants of Fredkin gate

Sometimes two outpus of Fredkin gate are swapped when constant bit is 0, sometimes when it is 1. What variant is right or more modern? If it was conscious decision to change behavior what was ...
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### Why isn't energy wasted with reversible computing? Isn't information discarded when we feed the function with a new input?

I understand that irreversible computing consumes energy because it has to "get rid" of outputs which have been used. With reversible computing that information is not "wasted" because with the ...
72 views

### How to Implement a reversible OR operator with a Fredkin gate (controlled swap)?

How to implement a reversible OR operator with a Fredkin gate ?
108 views

### What is the relation between reversible circuits and invertible functions?

A reversible circuit, if I understand it correctly, is a circuit where every gate in the circuit is invertible, i.e. can simply be “turned in the opposite direction”, so that the entire circuit can in ...
282 views

### How Janus (Reversible Programming Language) if, while, and Update Work

In Reversible Computing, all program statements are reversible. I understand for example that the following: \begin{align} x\ {+}&{=}\ 4\\ y\ {*}&{=}\ x\\ x\ {-}&{=}\ 10 \end{align} Has ...
83 views

### Reversible computation and no cloning theorem in quantum computing

I am having a problem in understanding a conflict between reversibility in quantum computation and the No cloning theorem. Given a function f, we construct the reversible version of f by adding ...
166 views

### How to prove Landauer's principle [closed]

I have some questions about energy emitted when one bit of information is processed. Landauer's principle states the minimum possible amount of energy required to erase one bit of information is <...
99 views

### How to model reversible interactive programs

Reversible programs with finite execution steps are well studied. For example, a Turing machine whose transitions are reversible and halts can be executed backwards consuming its tape in the reverse ...
373 views

### Is it possible to make N-way Controlled-NOTs out of Toffoli gates, without extra work bits?

I'm working on exercise 4.29 of Nielsen and Chuang: Find a circuit containing O(n^2) Toffoli, CNOT, and single qubit gates which implements a $C^n(X)$ gate (for n >3), using no work qubits. As ...
139 views

### What difference does it make when universal classical gates in quantum computation are reversible but not unitary?

As I've come across Grovers algorithm I dont understand why when computing F(X), which is an oracle function people use classical reversible circuits(toffoli, fredkin) to evaluate the circuit. Why can'...
Are there programming languages(or logic) that can implement(or express) a function $f:\mathbb{N}\to \mathbb{N}$ if and only if $f$ is a computable bijective functions?