IBM: realize the quantum advantage of fault tolerance by 2030

（ picture source ： The Internet ）

Ten years ago , Quantum computing is still a concept . Now , Researchers around the world are based on IBM Quantum cloud access service explores and realizes quantum applications , stay IBM, There are as many quantum circuits running every day 30 Billion .

Our dream is to create a useful fault-tolerant quantum computer , It has obvious quantum advantages , Can do things that classical processors can't do . It is expected to break the current computing limit , And CPU and GPU Together , Become a useful tool for human society .

But it is very difficult to build a kind of hardware to perform computation based on quantum mechanics , Noise is one of the basic challenges . lately ,IBM publish “‘ Mitigate quantum errors ’, Usher in the era of fault-tolerant quantum computers ” One article , Elaborated IBM How to be in 2023 Realize quantum advantage in .

IBM Quantum roadmap （ picture source ： The Internet ）

Methods to achieve practical quantum computing

The touchstone of practical quantum computing is to provide better than classical methods for solving useful problems “ advantage ”. This advantage can take many forms , The most prominent one ： Compared with classical algorithms , The running time of quantum algorithm has made a substantial leap . So , For specific types of problems , Quantum algorithms need to effectively represent quantum circuits .

How to optimize noisy qubits is a big obstacle for quantum computer engineers . essentially , The stronger the processing power of quantum computer , The more noisy its qubits are . at present , A common way to suppress noise is to scale qubits , So as to ensure the strength of the quantum bit measurement signal .

When quantum hardware is affected by different noise sources , Will highlight the performance of quantum bit decoherence 、 Single door error and measurement error . These errors limit the realizable depth of quantum circuits , And for shallow circuits , There is also noise error . In order to reduce the influence of noise on error ,IBM A complete set of solutions has been formed , It provides a solution to the problem of shallow and deep quantum circuit noise .

ZNE And PEC

In recent years ,IBM Two general quantum error mitigation methods have been developed and implemented ： Zero noise extrapolation (ZNE) And probabilistic error elimination (PEC).

ZNE, It refers to the calculation under different noise conditions , Based on this, the calculation results of quantum computer without noise are estimated , The study was published in 《Nature》 The journal .IBM call , This technology can improve the accuracy of quantum computing without improving the hardware , It can be used to improve any quantum computation that depends on the expected value . also ZNE The method has been proved to be able to study the ground state energy of small molecules .

PEC, Similar to the active noise reduction method in common noise reduction headphones , The system will be checked regularly for noise , Essentially invert these noise circuits , Output results with few errors .IBM Express , be based on PEC Method , They have run noise free estimators of quantum circuits on noisy quantum computers .

In this article ,IBM Some comparative examples of error correction circuits and classical circuits running on its quantum processing are also provided , And elaborated PEC The effect of the method will increase exponentially with the increase of circuit depth . meanwhile ,PEC The ability of the method to generate a noise free estimator can be clearly compared with accurate classical simulation .

Use PEC Quantum processors that mitigate errors are expected to outperform the corresponding classical algorithms

Hyperion Research Chief quantum analyst of Bob Sorensen Pointed out that ：“ It's not just error correction itself ,IBM The effort to reduce running time is shocking . They are shifting from abstract arguments to practical ones ： Improve applications at run time . Emphasizing runtime is an interesting point , The side shows IBM Three areas of research —— Circuit depth 、 Error rate and Algorithm . This lengthy article is IBM A summary of the steady development of quantum computing , And its in-depth explanation of the work of mitigating errors .”

IBM Director of quantum infrastructure Jerry Chow Express , We have shown great progress in using quantum hardware to expand solutions and accelerate classic processes , new “ Mitigate errors ” Strategy marks IBM From the discovery phase of fault-tolerant solutions to the landing phase .

Link to the original text ：

https://www.hpcwire.com/2022/07/19/new-ibm-blog-details-path-to-quantum-advantage-in-2023/

writing ：John Russell

compile ： Huike

edit ： Mu Yi

notes ： Ben Translated from “HPCwire”, Do not represent Quantum outpost view .