Coping with Errors in Quantum Computing

How far have we reached in dealing with quantum errors?
Kashyap Vyas

Quantum Mechanics is one of the revered branches of science, where the subject of study is about subatomic particles. With Quantum Mechanics, we have been able to study how very small particles in the world, in the range of atoms, electrons, and photons, behave in the world.

And their most noteworthy contribution to the world? Quantum Computers, Laser communication technologies, transistors, electron microscopes, etc.

However, Quantum information is subject to change based on many extenuation factors. Any change from the original value will result in an error, and Quantum Error Correction or (QEC) is used to keep the values in order.


In this article, let’s discuss some of the puzzling complexities of Quantum Mechanics, how they result in errors and how scientists are trying to correct them.

Quantum Mechanics and Relativity – Why they don’t mix!?

When we talk about Quantum Mechanics, we always associate it with atoms. But since the field of Quantum Mechanics is so advanced, we can even stretch it to explain the larger things, more specifically the everyday things around us, right?

No, contrary to this common belief, using quantum theory to explain large objects often returns false values. In a more science-oriented definition, we can say that Quantum Mechanics doesn’t bode well with the General Relativity that Einstein proposed.


To understand the gap between Quantum Mechanics and Theory of Relativity, we have to understand both in their basic definition and how they apply to the world.

In Quantum Mechanics, we study atom and even smaller particles like electrons. These subatomic particles are governed by a different set of rules than the laws of physics.  


For instance, Quantum theory states that particles like electrons have both particle nature and wave nature, and they are also capable of existing in two places at the same time. This doesn’t fit well in the macro world that we live in as the objects around us, be it a table or a ball, exists only in one place at a time.

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Another aspect of Quantum Mechanics is that it fails to explain Gravity. According to Quantum Mechanics, the passage of time and space are fixed.


However, according to Einstein, space and time are relative. Moreover, space can bend and contort. This is obviously a contraction to how Quantum Theory views things.

And this is where the errors that we talked about comes in. So how do scientists bridge this gap?

The perplexing conclusion

We cannot disregard both theories as both are equally right in their own ecosystem. When we take larger objects, the Theory of Relativity gives us accurate information on how the object responds and behaves in the presence of certain forces.

And, when we study the smallest particles in the universe, Quantum Mechanics paints a clear picture of their existence and how they interact with each other. We cannot have the same level of understanding of the quantum realm that we have today without Quantum Mechanics.

However, when micro and macro mechanics interact, they don’t provide answers for each other, creating errors in the calculations and findings. So what do we conclude?

Even now, with all our technological might, the errors of Quantum mechanics when scaled to macro proportions still stay elusive.

There are only two real explanations we have to come to terms with the problem.

Either the Quantum Mechanics is not universally applicable and hence, cannot be applied in terms of large objects. The other explanation for these errors is that physics lacks clear facts and certain possibilities that are beyond our recognition.

The only work around to this problem is to restrict the use of Quantum Mechanics to evaluate objects of certain sizes.

Coping with errors in quantum computing

However, there is a field where Quantum Mechanics is being used increasingly over the years – Quantum computing. Just like a personal computer, Quantum Computers are also built with imperfect parts.

The major difference is that there is a well-established system that is reserved just for fixing the errors on personal computers, while the same is not true for quantum computers.

Quantum computers process information in the form of Qubits. The qubits have the ability to become neither one nor zero and exits states in-between.

But, Qubits are very sensitive to external forces or the environment itself.  This paves the way for errors to chime in with the results.

The use of Logical Qubits

A senior scientist in Andreas Wallraff's research group named Sebastian Krinner might have the answer to that question. He is the first winner of the Lopez-Loreta Prize at ETH Zurich, and has come up with a concept that will help quantum computing make fewer errors.

Sebastian Krinner
Source: ETH Zurich/ D-PHYS/ Heidi Hostettler

His idea is to introduce a new type of qubit called a Logical Qubit. A logical qubit is a collection of the individual qubit.


So, instead of working individually, they work in unison, lower the error rate in the process. However, the condition for the Logic Qubit to work is that they must possess high-reliability rate from the beginning itself.

If they have an error rate of more than one percent, the Logic Qubit will bring in more errors, which is counterproductive. Experiments are being done to test out the Logic Qubits to study their effects on quantum computing.

Trapping ion string for error detection and correction

A different method is being developed to fix errors in Quantum computers on the fly. Ph.D. students Vlad Negnevitsky and Matteo Marinelli with the aid of postdoc Karan Mehta and other colleagues developed a system where they can measure the properties of two different species in a string, Beryllium ions (9Be+) and one Calcium ion (40Ca+).

The advantage of having two species to measure is that by the use of quantum properties, measuring the characteristics of one element will enable the researchers to know the state of the other element, without disturbing it.

The quantum correlations between two beryllium ions
Source: ETH Zurich/Home group

For example, monitoring Calcium ion will give the researchers information on the Beryllium ions. And the best part is that the ions can be held for multiple tests without disturbing the Beryllium ions, which was not possible with conventional quantum computing testing.

The team has also built a control system that would correct the Beryllium ions as soon as they veer off course. This form of error detection and correction was something unheard of in quantum computing.

It is clear that Quantum Mechanics come with its share of errors, but the level of computational power that they bring to the table makes them the only capable method for solving complex problems.

With research happening around the world to detect and correct the quantum errors, we are definitely moving faster towards practical quantum computing.

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