# Are composite gates within superconducting hardware implemented as a single pulse or as a series of pulses?

If we have for example a gate $$U^{\otimes2}$$, then within superconducting hardware, is the $$U$$ applied onto the first qubit and then the second or is a pulse corresponding to a composite gate (tensor product matrix) created which is applied onto both?

• are you asking whether one should think of $A\otimes B$ as $A$ being applied (to first qubit) before or after $B$ is applied to the second qubit (rather than the two gates being applied simultaneously)?
– glS
Sep 8, 2021 at 9:05
• I'm asking that in hardware, are the gates applied simultaneously as a single pulse, or individually as separate pulses? Sep 8, 2021 at 10:13
• Is $H$ the Hadamard gate? Sep 8, 2021 at 11:02
• If you want specifically to know what happens on the hardware level, you need to specify what hardware you are thinking of. Moreover, you might even need to specify what systems you are thinking of (e.g. those of IBM, or those of Google, or a specific chip of, let's say, Rigetti). Also realize that in pretty much all cases a Hadamard gate will never be implemented itself, but compiled to some other native gates.
– JSdJ
Sep 8, 2021 at 12:16
• Ok, I've changed the question to deal with an arbitrary native gate $U$, and have specified superconducting QCs Sep 8, 2021 at 14:43

• Re case 2: does it matter whether the qubits are entangled? $H$ applied to one qubit will commute with $H$ applied to another qubit, even if the qubits are entangled. Sep 8, 2021 at 11:02
• Sorry if I was unclear, but I don't mean $U^{\otimes2}$ mathematically, I'm asking how real devices implement composite gates Sep 8, 2021 at 14:46