Why is it important to eliminate the garbage qubits?

[bytebuster]

Why is it important to eliminate the garbage qubits?

Most reversible quantum algorithms use standard gates like Toffoli gate (CCNOT) or Fredkin gate (CSWAP). Since some operations require a constant |0⟩ as input and the number of inputs and outputs is equal, garbage qubits (or junk qubits) appear in the course of the computation.

So, a principal circuit like |x⟩ ↦ |f(x)⟩ actually becomes |x⟩ |0⟩ ↦ |f(x)⟩ |g⟩,
where |g⟩ stands for the garbage qubit(s).

Circuits that preserve the original value ends up with |x⟩ |0⟩ |0⟩ ↦ |x⟩ |f(x)⟩ |g⟩

I understand that garbage qubits are inevitable if we want the circuit to stay reversible, but many sources claim that it is important to eliminate them. Why is it so?

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Comments

[angerona]

I'd be interested

[bytebuster]

Great to hear!

I see you have paid account, and DW claims that

If you have a Paid, Premium Paid, or Seed account, any email sent to username@dreamwidth.org will automatically be forwarded to the email address you use on Dreamwidth.

So I've sent it via the StackExchange engine, pls let me know if it has been delivered yet.

[angerona]

haven't got it yet, but my spam filter may be catching it.

alternatively, lyudmila @ gmail works

[bytebuster]

Hmm, just sent it to various emails of mine, with no apparent result too. Let us wait. Sorry for inconvenience.

[bytebuster]

Тільки оце пригадав, що треба інвайт знову надіслати. Повідомте пліз, чи надійшло цього разу.

[angerona]

still nothing. What url is it coming from (at least the hostname), so that I can search for it specifically?

[bytebuster]

But… it was in the original post.
https://quantumcomputing.stackexchange.com/