Quantum Computing

A digitally controlled silicon quantum processing unit

HRL Laboratories demonstrates a fully integrated silicon quantum processing unit with cryogenic CMOS control that achieves order-of-magnitude improvements in exchange-only qubit fidelity and validates quantum error correction codes.

Research2 episodesPaper
In plain English

Imagine you want to build a super-powerful calculator that uses the weird rules of quantum physics to solve problems no regular computer can. The trouble is, the tiny quantum pieces — called qubits — are incredibly fragile and need to be kept colder than outer space. On top of that, you need wires and control signals going to every single qubit, and if you have thousands of them, the wiring becomes a nightmare. This team solved part of that puzzle by building their qubits out of silicon (the same stuff in your phone's chip), adding a tiny control computer that works at super-cold temperatures right next to the qubits, and using a special high-density cable to connect everything cleanly. They packed 54 tiny quantum dots onto a chip, arranged 18 of them into working qubits, and showed the qubits work about 10 times better than any previous silicon qubit of this type. They also ran basic error-correction experiments to prove the system is on track for real-world use.

On the show2
  1. EP 54

    How Quantum Computing Actually Works (Part 1)

    Part I of our quantum computing deep dive traces the field from Bell and Feynman to Deutsch and Shor—and explains what quantum computers actually do differently from classical machines.

    How Quantum Computing Actually Works (Part 1)
  2. EP 55

    Why Spin Qubits Will Win the Quantum Race (Part 2)

    Part II of our quantum computing deep dive compares the leading hardware architectures, and asks whether silicon’s greatest advantage is not simply making good qubits, but making quantum computers that can actually scale.

    Why Spin Qubits Will Win the Quantum Race (Part 2)
Key findings5
  1. 01

    Introduced a quantum processing unit (QPU) integrating a custom cryogenic CMOS controller, a high-density superconducting ribbon cable, and a low-noise exchange-only qubit device

  2. 02

    The quantum chip features a 3-rail array of 54 exchange-coupled quantum dots configurable to host up to 18 exchange-only qubits

  3. 03

    Demonstrated single-qubit and entangling gate performance advancing the exchange-only state of the art by an order of magnitude

  4. 04

    Validated the system by implementing a distance-5 repetition code and a distance-2 quantum error-detecting code with detailed comparisons to simulations

  5. 05

    All time-varying control signals are generated by a digitally programmed cryogenic CMOS controller and delivered via a high-density superconducting ribbon cable, enabling scalable control architecture

Abstract

Commercially relevant quantum computers will require large numbers of high-performing qubits that can be manufactured, integrated and controlled at scale. Silicon exchange-only qubits are a strong candidate modality owing to their control-signal simplicity and compatibility with advanced semiconductor manufacturing, but questions remain around the achievability of sufficiently low noise and a scalable control and wiring solution. Here we introduce a quantum processing unit composed of a custom-designed cryogenic complementary metal–oxide–semiconductor (CMOS) controller, a high-density superconducting ribbon cable and a low-noise exchange-only qubit device. The quantum chip features a 3-rail array of 54 exchange-coupled quantum dots, configurable to host up to 18 exchange-only qubits. We integrate and use these components to demonstrate qubit performance for both single-qubit and entangling operations that advances the exchange-only state of the art by an order of magnitude. We further validate this system by implementing a distance-5 repetition code and a distance-2 quantum error-detecting code and then make detailed comparisons with simulations. Our work facilitates the development of future utility-scale quantum computers with manageable operational and capital requirements.

Authors256

Members of the HRL Quantum Team and Collaborators, Michael Abraham, Edwin Acuna, Tower S. Adams, Moonmoon Akmal, Matthew R. Alfaro, I. Alvarado, Jacob Amontree, Carter Andrews, Reed W. Andrews, Michael Antcliffe, André R. Asencio, and 244 more

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