constructor(gates) {
        /** @type {!Array.<undefined|!Gate>} */
        this.gates = gates;
    }
A column of gates in a circuit with many qubits.

@param {!Array.<undefined|!Gate>} gates The list of gates to apply to each wire, with the i'th gate applying to
                                        the i'th wire.
Wires without a gate in this column should use undefined instead.