An EPR resonator for a cylindrical TE01n microwave mode, where n=1, 2, 3, or 4, has: a cylindrical body (10) which has an RF absorption of less than 5% at RFs below 1 kHz, a first plunger (11) delimiting the resonating volume within the body in an axial direction at a first end and a second plunger (12) delimiting the resonating volume within the body at a second end, the second plunger having an opening (13) for inserting an EPR sample. The first and second plunger each has a spiral winding of an electrically conductive filament wherein neither the ends nor neighboring turns of the spiral windings have electrically conductive connections prone to forming electrically closed loops. Using spiral winding plungers for cylindrical TE01n microwave modes provides equivalent functionality compared to conventional plungers, but without creating Eddy currents at frequencies lower than the frequency of the TE01n microwave mode.

According to one embodiment, an electronic circuit includes a band-pass filter, first circuits, a first port, and a second port. The band-pass filter includes filter resonators. Two adjacent filter resonators included in the filter resonators are mutually couplable. Each of the first circuits includes a first qubit and a first readout resonator. The first readout resonator is couplable with the first qubit. One of the filter resonators is couplable with the first readout resonator of one of the first circuits. Another one of the filter resonators is couplable with the first readout resonator of another one of the first circuits. The filter resonators include first, second, and third filter resonators. The first filter resonator is couplable with the first port. The second filter resonator is couplable with the second port. The third filter resonator is between the first filter resonator and the second filter resonator.

According to one embodiment, an electronic circuit includes a band-pass filter, first circuits, a first port, and a second port. The band-pass filter includes filter resonators. Two adjacent filter resonators included in the filter resonators are mutually couplable. Each of the first circuits includes a first qubit and a first readout resonator. The first readout resonator is couplable with the first qubit. One of the filter resonators is couplable with the first readout resonator of one of the first circuits. Another one of the filter resonators is couplable with the first readout resonator of another one of the first circuits. The filter resonators include first, second, and third filter resonators. The first filter resonator is couplable with the first port. The second filter resonator is couplable with the second port. The third filter resonator is between the first filter resonator and the second filter resonator.

A double loop antenna includes a source loop comprising: a spiral-shaped conductive source coil pattern disposed on a top surface of a board, and a source capacitor pattern comprising symmetrical conductive patterns disposed on the top surface and a bottom surface of the board; and a resonance loop comprising: a spiral-shaped conductive resonance coil pattern disposed on the bottom surface of the board, and a resonance capacitor pattern comprising symmetrical conductive patterns disposed on the top surface and the bottom surface of the board, wherein the source coil pattern and the resonance coil pattern are formed on different surfaces of the board.

A stereoscopic flexible resonator is provided. The stereoscopic flexible stereoscopic resonator includes at least one cell, at least one resonator including a capacitor, and a connection unit configured to connect the cell and the resonator in a stereoscopic structure.

A stereoscopic flexible resonator is provided. The stereoscopic flexible stereoscopic resonator includes at least one cell, at least one resonator including a capacitor, and a connection unit configured to connect the cell and the resonator in a stereoscopic structure.

A double loop antenna includes a source loop comprising: a spiral-shaped conductive source coil pattern disposed on a top surface of a board, and a source capacitor pattern comprising symmetrical conductive patterns disposed on the top surface and a bottom surface of the board; and a resonance loop comprising: a spiral-shaped conductive resonance coil pattern disposed on the bottom surface of the board, and a resonance capacitor pattern comprising symmetrical conductive patterns disposed on the top surface and the bottom surface of the board, wherein the source coil pattern and the resonance coil pattern are formed on different surfaces of the board.

A technique relates a superconducting microwave cavity. An array of posts has different heights in the cavity, and the array supports a localized microwave mode. The array of posts includes lower resonant frequency posts and higher resonant frequency posts. The higher resonant frequency posts are arranged around the lower resonant frequency posts. A first plate is opposite a second plate in the cavity. One end of the lower resonant frequency posts is positioned on the second plate so as to be electrically connected to the second plate. Another end of the lower resonant frequency posts in the array is open so as not to form an electrical connection to the first plate. Qubits are connected to the lower resonant frequency posts in the array of posts, such that each of the qubits is physically connected to one or two of the lower resonant frequency posts in the array of posts.

A technique relates a superconducting microwave cavity. An array of posts has different heights in the cavity, and the array supports a localized microwave mode. The array of posts includes lower resonant frequency posts and higher resonant frequency posts. The higher resonant frequency posts are arranged around the lower resonant frequency posts. A first plate is opposite a second plate in the cavity. One end of the lower resonant frequency posts is positioned on the second plate so as to be electrically connected to the second plate. Another end of the lower resonant frequency posts in the array is open so as not to form an electrical connection to the first plate. Qubits are connected to the lower resonant frequency posts in the array of posts, such that each of the qubits is physically connected to one or two of the lower resonant frequency posts in the array of posts.

A technique relates a superconducting microwave cavity. An array of posts has different heights in the cavity, and the array supports a localized microwave mode. The array of posts includes lower resonant frequency posts and higher resonant frequency posts. The higher resonant frequency posts are arranged around the lower resonant frequency posts. A first plate is opposite a second plate in the cavity. One end of the lower resonant frequency posts is positioned on the second plate so as to be electrically connected to the second plate. Another end of the lower resonant frequency posts in the array is open so as not to form an electrical connection to the first plate. Qubits are connected to the lower resonant frequency posts in the array of posts, such that each of the qubits is physically connected to one or two of the lower resonant frequency posts in the array of posts.