What are the top hurdles on the path to quantum computers?

1 Nov 2023

Image: © Bartek Wróblewski/Stock.adobe.com

From being prone to errors, sensitive to noise and requiring cold temperatures to operate, there are a lot of challenges researchers are tackling to create true quantum computers.

The path to a deep-tech breakthrough is not a straightforward one, which is especially true when it comes to quantum computers.

The concept has been around for decades and various prototype machines of varying power exist around the world. But they are currently in the early stages and are not fully reliable.

These powerful machines could eventually be able to solve complex calculations that would be essentially impossible for classic computers to work out. The potential for humanity is enormous, as quantum computers could help us push past certain tech bottlenecks and learn more about nature, chemistry and more.

The timeline for when the first true quantum computer will be created isn’t clear, but researchers around the world are working to make this machine a reality. To that end, let’s look at some of the biggest challenges facing this sector.

Quantum error correction

Arguably, one of the biggest issues in current quantum computers is the fact that they are unreliable and prone to calculation errors. These machines and their quantum bits – qubits – are so sensitive that various disturbances can lead to errors in their calculations.

Factors such as imperfect control signals, interference from the environment and unwanted interactions between qubits can lead to these disturbances, commonly referred to as “noise”. This issue becomes more severe as more qubits are added, which makes it a roadblock in scaling up quantum computers.

One way to resolve this issue is through quantum error correction, which is a more advanced form of the error correction that exists in classic computers.

Earlier this year, researchers at Google claimed to be able to improve the rate of quantum error correction by encoding information across various physical qubits into a “logical qubit”. The result also suggested that it may be possible to scale up the rate of error detection with more qubits.

In August, IBM claimed to have discovered new codes that work with 10 times fewer qubits, which gave the company hope that fault tolerant quantum computing may be possible without building an “unreasonably large quantum computer”.

In July, quantum computing company Quantiniuum claimed it was able to accurately simulate a hydrogen molecule by using an error-detecting code.

Meanwhile, researchers from MIT recently claimed to demonstrate a new form of qubit architecture that can perform operations at a much greater accuracy than previous examples.

Turn down the noise

While quantum error correction is one way to deal with noise, another potential trick could be to reduce the level of noise impacting these powerful machines.

Last year, a group of MIT researchers claimed to develop a technique that could make quantum circuits more resilient to noise.

These researchers created a framework that identifies the most robust quantum circuit for a particular computing task and then generates a mapping pattern.

They claimed that this method – called QuantumNAS (noise adaptive search) – is less computationally intensive than other search methods and could identify quantum circuits that improve the accuracy of machine learning tasks.

Earlier this year, a team of researchers at the University of Chicago said they developed a new method to constantly monitor the noise around a quantum system through the use of ‘spectator qubits’ – a set of qubits that are focused on measuring outside noise rather than storing data.

Moving to room temperature

Currently, quantum computers need to be in extremely low temperatures – close to absolute zero – in order to function properly. This uses more energy and makes it unfeasible for quantum computers to become more generally available.

But recent discoveries may be able to help these machines be used in warmer temperatures. One study released in June suggests the solution could be in graphene – the popular ‘wonder material’.

This study claimed that a combination of aminoferrocene and graphene materials possessed strong magnetic properties at room temperature, which could pave the way for future molecular magnets “as well as the design of qubit arrays and quantum systems”.

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Leigh Mc Gowran is a journalist with Silicon Republic