# Where are the physical gates in the Google processor?

Google's article Quantum supremacy using a programmable superconducting processor states that the processor "53 qubits, 1,113 single-qubit gates, 430 two-qubit gates, and a measurement on each qubit, for which we predict a total fidelity of 0.2%."

Where are the gates physically located? In the diagram, the qubits are the crosses and the qubits are the couplers.

• So the gates exist over time, in the 4th dimension? – vy32 Jan 21 at 14:39
• @Mark, can you make this an answer so that it can be improved and accepted? – vy32 Jan 21 at 14:39
• Yes, the quantum gates are sort of work in time dimension; quantum circuits are very different from classical circuits here. – kludg Jan 21 at 14:50

In relating quantum computing to classical computing there may be a small conceptual hurdle that needs to be overcome. Although a classical $$\mathsf{NAND}$$ gate may be implemented in hardware (say CMOS with a set of N- and P-type transistors), the idea of a quantum gate such as a $$\mathsf{CNOT}$$ or an $$\mathsf{H}$$ gate used in quantum computing most often is a little more subtle.
Conventionally a quantum circuit including a number of quantum gates acting on qubits usually is meant to read with time progressing from left to right. Most quantum gates are not so much physical as in classical computing on CMOS, but are rather well-timed laser, or in the case of Sycamore, microwave pulses on the qubits/couplers. These pulses may excite a qubit from $$\vert 0\rangle$$ to $$\vert 1\rangle$$ or act as one qubit controlling another qubit, etc. In this sense, quantum gates are much more like opcodes than like a set of transistors arranged in parallel/series in the classical sense.