I, Brian Wang, interviewed Andrei Petranko, Head of Product at Quantum Circuits and Neil Wu Becker, CEO and Co-founder of Nextbound - Advisor to Quantum Circuits.
This is the second interview and article on Quantum Circuits by Brian Wang of Nextbigfuture. The previous article is linked here.
The Equivalent of Built-in Checkbits
In conventional computer memory there are checkbits to detect errors. Checkbits in computer memory refer to additional bits used in error detection and correction schemes, particularly in the context of Error-Correcting Codes.
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.
The DRQ (Dual Rail Qubits) are double superconducting cavities. They encode one qubit in the single-photon subspace of two superconducting microwave cavities. One cavity represents the logical '0' state when it contains a photon, and the other represents the logical '1' state when it has the photon. If no photon is detected in either cavity, an erasure error is detected, indicating that the photon has been lost.
Quantum non-demolition (QND) measurements are used to check the state of the cavities without disturbing the quantum state. This allows for the detection of errors without collapsing the quantum information. The system uses an ancilla (like a transmon qubit) to perform these measurements, ensuring that it can detect the presence or absence of the photon in either cavity.
Quantum Circuits integrates real-time control features with error detection. Once an error is detected, the system can use this information to implement control flow decisions, like repeating sections of a quantum circuit or choosing different paths in algorithm execution based on the error state.
The Goal of Commercial Ready Quantum Computers
Quantum Circuits has the goal of first making components that are correct and then scaling the systems. This is part of the larger goal of making commercial ready quantum computers.
What is meant by commercial ready quantum computers ?
This means you can bet your business or company on the results of a quantum computer. Just as we rely today on servers and computers than provide services via cloud computer systems. Being able trust and rely on quantum computers means systems that are repeatable, predictable and trusted.
They have built an 8 qubit system and enterprise customers have been using them.
Customers have said that using error mitigation and error detection can enable them to get far more utility from Quantum Circuits than competing quantum computers.
Error suppression and error mitigation are common techniques and have intensive efforts by most quantum computer companies and the entire Quantum computer community.
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.
The superconducting system used by Quantum Circuits can operate at 4 megahertz while many other approaches are at 1 kilohertz. This means that if there were no errors or delays a superconducting QC system could perform 4 million operations in one second while it would take a 1 kilohertz system over one hour for that number of operations. Theoretically, 4 megahertz could perform in 8 hours what might take a slower system a year. This means the current experiments and exploration are done more quickly. In the future, it could mean useful quantum solutions might be produced more quickly.
Chief Scientist is a Legend in the Field
Robert Schoelkopf is Quantum's chief scientist. Robert Schoelkopf is a pioneering physicist who has made significant contributions to the field of quantum computing, particularly in the development of superconducting qubits. His achievements have propelled quantum computing research forward and laid the groundwork for practical quantum computers.
Together with colleagues Michel Devoret and Steven Girvin at Yale, Schoelkopf created the field of circuit quantum electrodynamics. Schoelkopf's team developed a quantum bus for information, enabling the transfer of quantum states between distant qubits.
He has developed several quantum algorithms and contributed to the field of quantum error correction.
The Quantum Circuits Acumen Seeker is an innovative quantum processing unit with the following specifications:
Qubit Count: It currently has 8 qubits.
Qubit Architecture: Utilizes dual-rail cavity qubits with built-in error detection, which includes quantum error detection (QED), error detection handling (EDH), and real-time control flow (RTCF).
Error Correction: The system is designed to enhance scalability and performance by integrating error detection directly into the qubit architecture, providing a pathway to fault-tolerant quantum computing without relying on brute-force scaling techniques.
Integration: It complements a full-stack quantum computing system that includes cloud services, a software development kit (SDK), and simulators.
Performance: The dual-rail qubit approach focuses on high fidelity and efficiency per qubit, aiming to achieve better results with fewer qubits compared to traditional scaling methods.
Application: This hardware is being used by enterprise customers for developing and testing quantum algorithms, highlighting its use in exploring quantum use cases across various industries.