Quantum computers are fundamentally different from traditional computers in the way they process data. Information processed as binary bits, or one’s or zero’s, is used by traditional computers. Quantum computers, on the other hand, send data through quantum bits, or qubits, which can be one, zero, or both at the same time. This is a simplification, and we will consider some details later, but superposition is at the heart of quantum computing’s promise of exponentially high computational power.

The opposition to such basic intricacies calls for brief generalisations. When The New York Times asked ten experts to describe quantum computing in 140 or fewer characters, some of their answers caused more problems than their answers:

“A quantum machine is a kind of analog calculator that computes by encoding information in the ephemeral waves that comprise light and matter at the nanoscale.”

David Reilly, a Microsoft researcher:

“If we’re honest, everything we currently know about quantum mechanics can’t fully describe how a quantum computer works.”

Alan Baratz, executive vice president of D-Wave Systems:

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What is a qubit? 

Bits are a sequence of electrical or optical pulses that represent 1s or 0s in today’s computers. Everything from your tweets and e-mails to your iTunes music and YouTube movies is made up of long sequences of these binary numbers.

Qubits, on the other hand, are subatomic particles such as electrons or photons that are used in quantum computers. Qubit manufacturing and management is a difficult scientific and technical task. Superconducting circuits are used by many firms including IBM, Google and Rigetti Computing at temperatures cooler than deep space. Others, such as the IonQ, use ultra-high-vacuum chambers to trap individual atoms in electromagnetic fields on a silicon chip. Its purpose is to separate the qubits into a controlled quantum state in both cases.

Because of the peculiar quantum characteristics of qubits, a connected group of them can provide far more processing power than the same amount of binary bits. One of these characteristics is superposition, while the other is entanglement.

What is superposition? 

Furthermore, qubits can represent a wide range of possible 1 and 0 combinations. Superposition is the ability to be in multiple states at the same time. Researchers use precise laser or microwave beams to manipulate the qubits into superposition.

This paradoxical characteristic allows a quantum computer to crunch through a large number of possible outcomes with multiple qubits in superposition at the same time. The final result of the calculation appears only when the qubits are measured, causing their quantum state to “collapse” to 1 or 0.

What is entanglement? 

Researchers can create “entangled” pairs of qubits, meaning that two members of a pair exist in the same quantum state. Changing the position of one qubit changes the position of the other in a predictable manner. Even if they are separated by great distances, it happens.

No one knows exactly how and why entanglement occurs. It even puzzled Einstein, who referred to it as “distant spooky activity.” Still, it is critical to the power of quantum computers.

When the number of bits in a computer is doubled, the computing power doubles. However, due to entanglement, adding more volume to a quantum machine rapidly increases its number-crunching capability.

To accomplish their magic, quantum computers use qubits entangled in quantum daisy chains. One of the reasons for their widespread interest is the ability of computers to accelerate calculations using specially built quantum algorithms.

The good news is that this is the case. The bad news is that because of the clutter, quantum computers are far more error-prone than conventional computers.

What is decoherence? 

Decoherence is defined as the interaction of qubits with their surroundings in such a way that their quantum activity decreases and eventually disappears. His quantum state is in danger. The tiniest vibrations or temperature changes—what quantum physicists call “noise”—could prompt them to break out of superposition before they could work. This is why researchers use supercooled fridges and vacuum chambers to keep qubits safe from the outside world.

Despite his efforts, Shor continues to make mistakes in calculations. Some of that can be compensated for using clever quantum algorithms, and adding additional qubits can help as well.

However, a single, extremely reliable “logical” qubit would certainly require thousands of simple qubits. This will significantly reduce the processing capacity of quantum computers.

The problem is that researchers haven’t been able to make more than 128 standard qubits so far (see our qubit counter here). As a result, we are still far from widely used quantum computers.

Pioneers’ hopes of becoming the first to demonstrate “quantum supremacy” have not been dashed.

What is quantum supremacy?

This is the moment when a quantum computer can perform a mathematical calculation that even the most powerful supercomputer cannot handle.

As researchers continue to develop new algorithms to improve the performance of classical machines and improve supercomputing technology, it is still uncertain how many qubits will be needed to achieve this. However, researchers and businesses are vying for the title to test them on some of the world’s most powerful supercomputers.

There is a lot of discussion in the scientific community about how meaningful it will be to reach this point. Instead of waiting for the announcement of dominance, businesses such as IBM, Rigetti and Canadian startup D-Wave are already experimenting with quantum computers. Quantum machines are also available through Chinese companies like Alibaba. Quantum computers are being purchased by some firms, while others are employing computers made accessible through cloud computing services.

Where is it most likely that a quantum computer would be most beneficial first?

Simulating the behavior of matter down to the molecular level is one of the most promising uses of quantum computers. Quantum computers are being used by automakers such as Volkswagen and Daimler to mimic the chemical structure of electric car batteries to identify new ways to increase their performance. Pharmaceutical firms are using them to compare and evaluate substances that could lead to the development of new drugs.

Machines are also ideal for solving optimization issues because they can quickly sift through a large number of alternative solutions. For example, Airbus uses them to help calculate the most fuel-efficient climb and descend trajectories for an airplane. Volkswagen has also developed a tool that estimates the best bus and taxi routes in cities to reduce congestion. Some academics believe that the tools could potentially be used to accelerate the development of artificial intelligence.

It could take years for quantum computers to fulfill their promise. The universities and corporations working on them are facing a lack of qualified researchers in the field as well as a shortage of essential component suppliers. However, if these strange new computing devices live up to their hype, they have the potential to revolutionize entire fields and accelerate global innovation.

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