Quantum Circuits Make Error Detecting Qubits | NextBigFuture.com

Quantum Circuits recently raised $60 million in a new funding round and they have just announced a new unique superconducting hardware system drives more efficiency with error-detecting dual-rail qubits. They have new software, simulator, and cloud service for full-stack enterprise solution that corrects first, then will be able to scale.

Quantum Circuits, Inc., announced highly efficient, scalable hardware that rounds out its full-stack quantum computing system, accelerating the path to fault tolerance and commercial readiness with an industry first featuring error detection built into powerful dual-rail cavity qubits.

The highly efficient 8-qubit quantum processor is called Aqumen Seeker. Three months ago they announced a quantum cloud service,
software development kit, and simulator to build and test quantum applications before they run on production hardware.

Brian Wang, of Nextbigfuture interviewed Quantum Circuit CEO Ray Smets and Head of Product Andrei Petrenko.

Superconducting Dual Resonator Qubits

They described how their superconducting system uses spherical chambers with reflective mirrors inside to hold a photon. They use RF frequencies to control the movement and actions of the photon. The different RF frequencies determine if the photon can pass between the chambers. Currently, the chambers each have a diameter of 5 millimeters. They wlll shrink those down to microscopic size in later generations.

Superconducting Dual Resonator Qubits enhance the fidelity of quantum applications with error detection and correction.

There are two superconducting resonators (aka cavities) connected by a so-called “coupler.”

A superconducting qubit (transmon) connected to one of the resonators, which in turn is itself connected to a measurement device.

The resonators are the workhorse. They encode the logical information. If there is one microwave photon in the top resonator, the DRQ is in the state 0. Conversely, if there is one microwave photon in the bottom resonator, the DRQ is in the state 1.

Every quantum computer requires a universal gate set, and for DRQs this is achieved by the following operations:

1. Single qubit operations are simple: apply signals to the coupler that separates the two resonators, turning on what’s called a beam-splitter.  A bit flip equates to a full transfer of a photon from top to bottom (or vice-versa), and superpositions are created by applying modified versions of a similar beam-splitter signal.

2. Measurements are performed by entangling the transmon qubit with the photons in the resonators and then measuring the transmon.

3. Two qubit gates are realized by entangling the nearest resonators of neighboring DRQs and applying coordinated control signals, leveraging the transmon ancilla when needed.

Throughout the steps of an algorithm, you place erasure checks to see if the DRQs have undergone any erasure errors. At the end of the algorithm, if you keep only the data where you didn’t measure any erasure errors during your checks, you’re much more likely to obtain a high-quality result.

Colleagues at Yale (Shruti Puri and Steve Girvin, among others), have shown that it is much easier to implement error correction when erasure errors are the dominant source of loss in the system, rather than bit or phase flips.

PNAS – Applied Physical Sciences – Dual-rail encoding with superconducting cavities (2023)

Nature Physics – A superconducting dual-rail cavity qubit with erasure-detected logical measurements July 2024

More on the Announced System

Quantum Circuits new processor is now being used by enterprise customers with the software as a full-stack system.

Quantum Circuits’ error-detecting dual-rail qubits innovation allows errors to be detected and corrected first to avoid disrupting performance at scale. This system will enable about 10-20 physical quantum qubits instead of 200 physical qubits for each error correct logical qubit.

Quantum Circuits’ dual-rail qubits incorporate the industry’s only combination of quantum error detection (QED), error detection handling (EDH), and real-time control flow (RTCF). RTCF and EDH enhance tools that programmers use to explore and create algorithms with Quantum Circuits’ dual-rail qubits. These features significantly enhance the performance of the quantum system, enabling algorithms to run efficiently with greater scale, fidelity, and reliability.

Efficient error correction is the cornerstone of our approach to accelerating the roadmap to fault tolerance and quantum advantage. Comprised of eight Dual-Rail Cavity Qubits (DRQs), the Seeker is a milestone on this timeline. DRQs are a unique approach to building and deploying the physical qubit. They still provide the same universal quantum computational capability as other platforms in the industry, but they also introduce error detection as a built-in hardware feature. This can let the user know, with high fidelity, which DRQ has an error at which point in the algorithm. Not only is this a valuable addition to near-term quantum algorithm design workflows, it is an essential bridge to faster error correction. It reduces the hardware needed to realize scalable quantum computing, thereby hastening the era of fault tolerance.

With the release of this QPU, Quantum Circuits rounds out its full stack offering, providing Seeker access via the Aqumen Cloud service with full integration with our SDK and Simulator. Our Alpha Program partners will enjoy full access as we ramp up online availability. They will have the opportunity to execute programs written in our fully featured QCDL programming framework, together with Qiskit, on the only QPU that can execute hardware-native error detection operations in the industry.