Posts in category: Quantum Computing

What is quantum computing?

Quantum computing is a powerful technology that uses quantum mechanical phenomena, such as superposition and entanglement, to perform computations that are beyond the reach of today’s classical computers.

Quantum computers use qubits, which can exist in a combination of two states at the same time, unlike classical bits that can only be either 0 or 1. Quantum computers can exploit this property to perform parallel operations on multiple qubits, which can speed up certain calculations exponentially.

Quantum computing has certainly the potential to transform the world by enabling new discoveries in fields such as physics, chemistry, cryptography, artificial intelligence and more.

Quantum computing still faces many challenges, such as maintaining the coherence and fidelity of qubits, designing efficient quantum algorithms and scaling up the number of qubits. Quantum computing is still a field in its early stages of development and research, but I expect it to have a significant impact on society in the future.

How does a quantum computer work?

A quantum computer works by using quantum bits, or qubits, which are physical systems that can exist in a superposition of two states, such as 0 and 1. Unlike classical bits, which can only store one value at a time, qubits can encode both values simultaneously, which allows them to perform parallel operations on multiple inputs.

A quantum computer manipulates qubits using quantum gates, which are devices that apply specific transformations to qubits. By applying a sequence of quantum gates, a quantum computer can implement a quantum algorithm, which is a set of instructions that exploits quantum phenomena to solve a problem.

However, qubits are also very sensitive to noise and interference from their environment, which can cause them to lose their quantum properties and produce errors. This is known as quantum decoherence, and it is one of the main challenges of quantum computing. To prevent or correct decoherence, quantum computers use various techniques such as error correction codes, fault-tolerant architectures and low-temperature cooling systems.

How to build a quantum computer?

There are different approaches to build a quantum computer, depending on the choice of physical system that can be used as qubits and the methods of manipulating and controlling them. Some of the most common approaches are:

• Superconducting qubits: These are circuits made of superconducting materials that can behave as artificial atoms with two energy levels. They can be coupled to microwave resonators and controlled by microwave pulses. This is the pioneering approach used by IBM, Google and Intel.
• Ion trap qubits: These are devices that use electric fields to trap and manipulate individual charged atoms (ions) that have two internal states. They can be controlled by laser beams and interact with each other through their electric fields. This is the approach used by IonQ and Honeywell.
• Spin qubits: These are electrons or nuclei that have two spin states. They can be embedded in solid-state materials such as silicon or diamond, and controlled by electric or magnetic fields. They can also interact with each other through their spin couplings. This is the approach used by Microsoft and Intel.
• Topological qubits: These are exotic quasiparticles that emerge from certain materials under extreme conditions, such as low temperature and high magnetic field. They have two topological states that are immune to local noise and decoherence. They can be controlled by braiding their paths around each other. This is the approach pursued by Microsoft and IBM.
• Photons: These are particles of light that can have two polarization states. They can be manipulated by optical devices such as beam splitters and phase shifters, and interact with each other through nonlinear media or detectors. This is the approach used by Xanadu and PsiQuantum.

These are some of the main approaches to build a quantum computer, but there are also others that use different physical systems or methods, such as atoms, molecules, defects, nanowires, etc.

Which is the most promising approach?

Each of these approaches has its own advantages and disadvantages. Superconducting qubits are very accurate, but they are also very difficult to control. Ion trap qubits are very controllable, but they are also very fragile. Topological qubits are very promising, but they are still in their early stages of development.

It is still too early to say which approach will be the most successful in building a quantum computer. All of these approaches are actively being pursued by researchers around the world. That is what makes this nascent field so exciting!

Three years ago, Google’s quantum computers achieved a computational task that the fastest supercomputers could not. That milestone was significant for the company’s goal of building a large-scale quantum computer, but it was only one step toward making quantum applications useful for human progress. There is more to do for Google’s quantum computers to achieve a breakthrough against world poverty.

Quantum computing is a rapidly-emerging technology that harnesses the laws of quantum mechanics to solve problems too complex for classical computers. Quantum computers use quantum bits or qubits, which can exist in superpositions of two states (0 and 1) and entangle with each other. This allows quantum computers to perform parallel computations and exploit quantum interference. However, qubits are also very sensitive to noise, which can destroy their quantum properties and affect the accuracy of the computation, a phenomenon called decoherence.

This is where quantum error correction, a set of methods to protect quantum systems from decoherence, comes handy. It encodes quantum information across multiple physical qubits to form a “logical qubit,” which can be used for computation instead of individual qubits. This is believed to be the only way to produce a large-scale quantum computer with low enough error rates for useful calculations. Quantum error correction is essential for fault-tolerant quantum computing that can run more powerful algorithms, such as predicting the weather or enabling metaverses for millions of virtual users.

This is where the significance of Google’s milestone lies. The company has shown, for the first time, that it’s possible to reduce errors by increasing the number of qubits. Instead of working on the physical qubits on a quantum processor individually, researchers are treating a group of them as one logical qubit. As a result, a logical qubit that Google made from 49 physical qubits was able to outperform one the company made from 17 qubits.

The achievements of researchers from Google and other companies are certainly inspiring. They remind me of the days when traditional computers filled spaces as big as football fields. Quantum computing today has countless potential applications across various domains and industries. For example:

• Quantum computers can enhance machine learning algorithms by speeding up data processing, feature extraction, model training and inference.
• Quantum computers can simulate complex molecular systems and chemical reactions that are beyond the reach of classical computers. This will lead to new discoveries in drug development, energy storage, fertilization, and solar capture, among other areas.
• Quantum computers can solve hard optimization problems that involve finding the best solution among many possible ones. Do you remember the traveling salesman problem? This can improve efficiency and reduce costs in areas such as manufacturing, industrial design, traffic management, supply chain management and more.
• Quantum computers can perform faster and more accurate calculations for asset valuation, risk analysis, trading strategies, fraud detection and more. I have widely spoken about how they can enhance encryption methods and break existing ones, unless quantum-proof methods are developed.

According to the World Bank, more than 700 million people lived in extreme poverty in 2020. This means that about 9.3 percent of the world’s population had to survive on less than $1.90 a day. I hope quantum computing will help fight world poverty by enabling new solutions and innovations in areas such as climate change, healthcare, food security, and education. That is why it is so important to ensure that quantum computing is developed ethically and responsibly for the benefit of mankind.