Tech at Polsky

Fast Flux Control of High-Q 3D Multimode Cavities

Inventor(s):

Technology Classifications > Quantum Sciences

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SUMMARY

3D microwave cavities are advantageous platforms for quantum computation due to their lengthy coherence times and fast control of quantum states when interfaced with superconducting qubits. Fast magnetic control of these cavities is crucial in tuning frequencies and interactions of superconducting qubits to efficiently manipulate quantum states.
While fast local magnetic control has been realized for planar 2D architectures, the challenge remains in their 3D counterparts. Limitations posed by nonlocal magnetic field flux lines compromise coherence lifetimes and are not rapidly switchable. This technology is a design that overcomes these limitations to achieve fast flux control of localized magnetic fields in high-Q 3D microwave cavities.
The design incorporates a fast flux bias line that is inserted in a slot between two seamless 3D cavities.These cavities are more conducive to supporting higher frequency transverse electromagnetic waves than current cavity modes of interest. The flux line of the device is also patterned to simulate a low pass filter that insulates the cavity, thus protecting different frequency modes and increasing accuracy.
Previous attempts of these devices were limited to exclusive use of DC flux biases which prohibited fast flux control. Other technologies that utilize AC magnetic fields on superconducting qubits improved fast flux control but reduced coherence lifetime and encouraged significant cross talk between qubits. This design simultaneously improves coherence quality factors by almost two orders of magnitude while maintaining interactions between superconducting qubits.

FIGURE

(a) Cut away view showing the structure of the 3D cavity. The flux bias chip sits in the slot between the two cavities marked by yellow arrow. (b) Design of the flux bias control chip. It consists of large capacitive pads separated by thinner inductive lines to act as a filter. The two cavities marked in (a) are also shown colored in blue and green. (c) The flux line (pink) is terminated in a loop placed near to a SQUID loop. The Josephson junctions are shown as two black rectangles. Two metal pads colored blue and green couple to the electric fields of the two cavities.

ADVANTAGES

Maintains lengthy coherence lifetimes
Combats limited usage of DC flux biases with AC magnetic fields
Fast flux control of localized magnetic fields
Cavities support higher frequency transverse electromagnetic waves

APPLICATIONS

Quantum Computing
3D Cavity Design and Control

PUBLICATIONS

https://meetings.aps.org/Meeting/MAR22/Session/N34.6

TECH DETAILS

Published
9/7/2022

Reference ID
22-T-136