This is my first question here. I've started doing research in quantum computing. In Digital Logic circuits, there are many circuits (like parity generator, checker, demux etc.) that can be implemented using reversible logic. My questions are the following;

  1. can we design that same circuits using IBM quantum lab or we cannot?
  2. How do we understand that which circuits can be designed using quantum gates?
  3. What are various parameters that can be analysed here?

1 Answer 1


Both Toffoli[1] and Fredkin[2] gates; which are universal for classical reversible computation; are quantum gates. And both of them can be used directly in IBM Quantum Lab[3, 4].

So, you can design same reversible circuits using same gates.

  • $\begingroup$ Thank you for answer..Yes.. But using those gates the other digital circuits can be designed?? I got this doubt.. $\endgroup$
    – Arpita
    Apr 7, 2022 at 14:09
  • $\begingroup$ This is what universality means. It means that one can use Toffoli gates only (or Fredkin gates only) to build circuits that can perform any desired boolean function computation in a reversible manner (we may need to add some extra ancilla bits to achieve this). However, they are not universal for quantum computation. First link in my answer talk about the universality idea. And for more details see here (PDF) $\endgroup$ Apr 7, 2022 at 16:39

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