A new microwave resonator readout scheme for superconducting qubits

We address the scaling-up problem for superconducting quantum circuits by using lumped-element resonators based on an alternative fabrication method of aluminum-aluminum oxide-aluminum (Al- ${\mathrm{AlO}}_{x}$ -Al) parallel-plate capacitors. The size of the resonators is only $0.04\phantom{\rule{0.2em}{0ex}}{\mathrm{mm}}^{2}$ , which is more than one order smaller than the typical size of coplanar resonators ( $1\phantom{\rule{0.2em}{0ex}}{\mathrm{mm}}^{2}$ ). The fabrication method we develop easily fits into the standard superconducting qubit fabrication process. We obtain capacitance per area $14\phantom{\rule{0.2em}{0ex}}\mathrm{fF}/\text{\ensuremath{\mu}}{\mathrm{m}}^{2}$ and the internal quality factor $1\ifmmode\times\else\texttimes\fi{}{10}^{3}$--$8\ifmmode\times\else\texttimes\fi{}{10}^{3}$ at the single-photon level. Our results show that such devices based on Al- ${\mathrm{AlO}}_{x}$ -Al capacitors could be further applied to the qubit readout scheme, including resonators, filters, amplifiers, as well as microwave metamaterials and innovative types of qubits, such as $0\ensuremath{-}\ensuremath{\pi}$ qubit.We address the scaling-up problem for superconducting quantum circuits by using lumped-element resonators based on an alternative fabrication method of aluminum-aluminum oxide-aluminum (Al-${\mathrm{AlO}}_{x}$-Al) parallel-plate capacitors. The size of the resonators is only $0.04\phantom{\rule{0.2em}{0ex}}{\mathrm{mm}}^{2}$, which is more than one order smaller than the typical size of coplanar resonators ($1\phantom{\rule{0.2em}{0ex}}{\mathrm{mm}}^{2}$). The fabrication method we develop easily fits into the standard superconducting qubit fabrication process. We obtain capacitance per area $14\phantom{\rule{0.2em}{0ex}}\mathrm{fF}/\text{\ensuremath{\mu}}{\mathrm{m}}^{2}$ and the internal quality factor $1\ifmmode\times\else\texttimes\fi{}{10}^{3}$--$8\ifmmode\times\else\texttimes\fi{}{10}^{3}$ at the single-photon level. Our results show that such devices based on Al-${\mathrm{AlO}}_{x}$-Al capacitors could be further applied to the qubit readout scheme, including resonators, filters, amplifiers, as well as microwave metamaterials and innovative types of qubits, such as $0\ensuremath{-}\ensuremath{\pi}$ qubit.

arXiv:2203.09592Physical Review AppliedApr 24, 202314 citations

Microwave readout scheme for a Josephson phase qubit

Tobias Wirth, Jürgen Lisenfeld, Alexander V. Lukashenko +1 more

We present experimental results on a microwave scheme for reading out a Josephson phase qubit. A capacitively shunted superconducting quantum interference device (SQUID) is used as a nonlinear resonator which is inductively coupled to the qubit. The flux state of the qubit is detected by measuring the amplitude and phase of a microwave pulse reflected from the SQUID resonator. By this low-dissipative method, the qubit state measurement time is reduced to 25 μs, which is much faster than the conventional readout performed by switching the SQUID to its nonzero dc voltage state. The readout scheme presented here allows for reading out multiple qubits using a single microwave line by employing frequency-division multiplexing.We present experimental results on a microwave scheme for reading out a Josephson phase qubit. A capacitively shunted superconducting quantum interference device (SQUID) is used as a nonlinear resonator which is inductively coupled to the qubit. The flux state of the qubit is detected by measuring the amplitude and phase of a microwave pulse reflected from the SQUID resonator. By this low-dissipative method, the qubit state measurement time is reduced to 25 μs, which is much faster than the conventional readout performed by switching the SQUID to its nonzero dc voltage state. The readout scheme presented here allows for reading out multiple qubits using a single microwave line by employing frequency-division multiplexing.

arXiv:1010.0954Applied Physics LettersDec 27, 201013 citations

Resonator-based superconducting qubit

Ivan N. Zhilyaev

Russian MicroelectronicsNov 1, 20050 citations

Scalable Piezo-Optomechanical Transducer Matched to a Superconducting Qubit for Optical Readout

Kiki L. Schuurman, Thierry Christiaan van Thiel, Matthew J. Weaver +16 more

We demonstrate a piezo-optomechanical transducer, which uses an intermediate mode to transduce signals from the microwave to the optical domain. The device is a hybrid platform, combining a superconducting microwave resonator with a piezoelectric interface and a optomechanical nanobeam. The microwave frequency of the transducer can be matched to a superconducting qubit. Subsequently, an optical single-shot readout of a qubit using a demolition readout technique is demonstrated with a fidelity of 81 %. With enhanced transducer performance and the addition of optical qubit control to the system, the system is capable of supporting all-optical readout and control of a large number of qubits in parallel.We demonstrate a piezo-optomechanical transducer, which uses an intermediate mode to transduce signals from the microwave to the optical domain. The device is a hybrid platform, combining a superconducting microwave resonator with a piezoelectric interface and a optomechanical nanobeam. The microwave frequency of the transducer can be matched to a superconducting qubit. Subsequently, an optical single-shot readout of a qubit using a demolition readout technique is demonstrated with a fidelity of 81 %. With enhanced transducer performance and the addition of optical qubit control to the system, the system is capable of supporting all-optical readout and control of a large number of qubits in parallel.

International Conference on Solid-State Sensors, Actuators and MicrosystemsJun 29, 20250 citations

Novel microwave readout for phase qubits

Shwetank Kumar, Matthias Steffen, Mary-Beth Rothwell +3 more

Bulletin of the American Physical SocietyMar 17, 20100 citations

We address the scaling-up problem for superconducting quantum circuits by using lumped-element resonators based on an alternative fabrication method of aluminum-aluminum oxide-aluminum (Al-

{\mathrm{AlO}}_{x}

-Al) parallel-plate capacitors. The size of the resonators is only

0.04\phantom{\rule{0.2em}{0ex}}{\mathrm{mm}}^{2}

, which is more than one order smaller than the typical size of coplanar resonators (

1\phantom{\rule{0.2em}{0ex}}{\mathrm{mm}}^{2}

). The fabrication method we develop easily fits into the standard superconducting qubit fabrication process. We obtain capacitance per area $14\phantom{\rule{0.2em}{0ex}}\mathrm{fF}/\text{\ensuremath{\mu}}{\mathrm{m}}^{2}$ and the internal quality factor $1\ifmmode\times\else\texttimes\fi{}{10}^{3}$--$8\ifmmode\times\else\texttimes\fi{}{10}^{3}$ at the single-photon level. Our results show that such devices based on Al-

{\mathrm{AlO}}_{x}

-Al capacitors could be further applied to the qubit readout scheme, including resonators, filters, amplifiers, as well as microwave metamaterials and innovative types of qubits, such as $0\ensuremath{-}\ensuremath{\pi}$ qubit.