REDUCING SPONTANEOUS EMISSION IN CIRCUIT QUANTUM ELECTRODYNAMICS BY A COMBINED READOUT AND FILTER TECHNIQUE

摘要

A mechanism relates a superconductor circuit. A Δ circuit includes a first node connecting a Purcell capacitor to a qubit coupling capacitor, a second node connecting the Purcell capacitor to a readout coupling capacitor, and a third node connecting the qubit coupling capacitor to the readout coupling capacitor. A qubit is connected to the first node and has a qubit frequency. A readout resonator connects to the third node combining with the Purcell capacitor to form a filter. Capacitance of the Purcell capacitor is determined as a factor of the qubit frequency of the qubit and blocks emissions of the qubit at the qubit frequency. Capacitance of the Purcell capacitor causes destructive interference, between a first path containing Purcell capacitor and a second path containing both the qubit coupling capacitor and readout coupling capacitor, in order to block emissions of the qubit at the qubit frequency to the external environment.

主权项

1. A superconductor circuit comprising:
a delta (Δ) circuit comprising a first node connecting a Purcell capacitor (CP) to a qubit coupling capacitor (Cq), a second node connecting the Purcell capacitor (CP) to a readout coupling capacitor (Cc), and a third node connecting the qubit coupling capacitor (Cq) to the readout coupling capacitor (Cc); a qubit connected to the first node, wherein the qubit has a qubit frequency; a readout resonator connected to the third node, wherein the readout resonator combines with the Purcell capacitor (CP) to form a filter; and the second node configured for connection to an external environment; wherein capacitance of the Purcell capacitor (CP) is determined as a factor of the qubit frequency of the qubit, such that the capacitance of the Purcell capacitor (CP) blocks emissions of the qubit at the qubit frequency to the external environment; and wherein the capacitance of the Purcell capacitor (CP) is set to cause destructive interference, between a first path containing the Purcell capacitor (CP) and a second path containing both the qubit coupling capacitor (Cq) and the readout coupling capacitor (Cc), at the qubit frequency in order to block the emissions of the qubit at the qubit frequency to the external environment.