Josephson junctions for improved qubits

Abstract

A technique relates to a superconducting qubit. A Josephson junction includes a first superconductor and a second superconductor formed on a non-superconducting metal. A capacitor is coupled in parallel with the Josephson junction.

What is claimed is: 
     
         1 . A method of forming a microwave device comprising:
 providing a superconducting qubit, the superconducting qubit including a Josephson junction having a first superconductor, a second superconductor, and a non-superconducting metal; and   coupling a readout resonator to the superconducting qubit.   
     
     
         2 . The method of  claim 1 , wherein the first superconductor and the second superconductor are separated from one another. 
     
     
         3 . The method of  claim 1 , wherein a space separates the first superconductor and the second superconductor. 
     
     
         4 . The method of  claim 3 , wherein a dimension of the space is about 0.1-10 microns. 
     
     
         5 . The method of  claim 1 , wherein the non-superconducting metal is formed on a semiconductor. 
     
     
         6 . The method of  claim 1 , wherein the non-superconducting metal comprises copper. 
     
     
         7 . The method of  claim 1 , wherein the non-superconducting metal comprises platinum. 
     
     
         8 . The method of  claim 1 , wherein the readout resonator is a two-dimensional planar waveguide. 
     
     
         9 . The method of  claim 1 , wherein the readout resonator is a three-dimensional cavity. 
     
     
         10 . The method of  claim 1 , further comprising a port, the port being operable to receive microwave signals. 
     
     
         11 . The method of  claim 10 , wherein the port is capacitively coupled to the readout resonator. 
     
     
         12 . The method of  claim 1 , further comprising a port, the port being operable to transmit microwave signals reflected from the readout resonator. 
     
     
         13 . The method of  claim 1 , wherein the superconducting qubit is capacitively coupled to the readout resonator. 
     
     
         14 . The method of  claim 1 , wherein the readout resonator is operable to read out a state of the superconducting qubit. 
     
     
         15 . The method of  claim 1 , wherein the readout resonator is operable to read out a state of the superconducting qubit in reflection. 
     
     
         16 . The method of  claim 1 , wherein the first superconductor and the non-superconducting metal form a stack. 
     
     
         17 . The method of  claim 1 , wherein the second superconductor and the non-superconducting metal form a stack. 
     
     
         18 . The method of  claim 1 , wherein the first superconductor is positioned away from the second superconductor. 
     
     
         19 . The method of  claim 1 , wherein the non-superconducting metal contacts both the first and second superconductors. 
     
     
         20 . The method of  claim 1 , wherein a junction region is formed between the first and second superconductors.