Quantum Computing Development Roadmap

The Road to Quantum Advantage

- Overview

In the field of quantum computing, a 1 or 0 is not stored as an ordinary bit, but as a qubit. What makes a qubit different is that it can be both a 1 and a 0 at the same time, potentially enabling quantum computers to shine through more advanced calculations that take classical computers orders of magnitude longer to complete. 

Qubits are the basic unit of quantum information, and their number is one of the measures of quantum computer capabilities. 

The road has been long and considerable progress has been made. In 1998, we had two qubits in the lab that couldn't preserve quantum information long enough to be useful. By 2024, we will have 256 qubits accessible through the cloud that can store quantum information long enough to demonstrate computation. In the lab, we have two quantum computers, each with over 1,000 qubits. 

Quantum computers still have a long way to go before they can reliably reach that speed or be practical in everyday use. First, qubits require an extremely controlled environment, where slight perturbations, such as tiny changes in temperature, can cause qubits to lose their quantum state -- and their information.

Some companies that have quantum computing roadmaps include:

• IBM: IBM's 10-year plan includes developing new quantum processors, software, and services, as well as creating a software error-correction code. The roadmap also focuses on quantum-centric supercomputing, which uses a heterogeneous computing architecture that combines quantum and classical computation.
• Infleqtion: Infleqtion's five-year roadmap, called Scorpius, aims to make commercial quantum computing a reality within five years. The roadmap focuses on making commercial scale computation accessible in areas like material science, energy, and machine learning.
• QuEra: QuEra's roadmap focuses on developing large-scale, fault-tolerant quantum computers that can solve problems that are difficult for classical computers. The roadmap includes goals like reaching 100 logical error-corrected qubits by 2026.

- How Do Quantum Computers Work?

Quantum computers perform calculations based on the probability of an object's state before it is measured - instead of just 1s or 0s - which means they have the potential to process exponentially more data compared to classical computers. Classical computers carry out logical operations using the definite position of a physical state. These are usually binary, meaning its operations are based on one of two positions. A single state - such as on or off, up or down, 1 or 0 - is called a bit.  

In quantum computing, operations instead use the quantum state of an object to produce what's known as a qubit. These states are the undefined properties of an object before they've been detected, such as the spin of an electron or the polarisation of a photon. Rather than having a clear position, unmeasured quantum states occur in a mixed 'superposition', not unlike a coin spinning through the air before it lands in your hand. These superpositions can be entangled with those of other objects, meaning their final outcomes will be mathematically related even if we don't know yet what they are.  

The complex mathematics behind these unsettled states of entangled 'spinning coins' can be plugged into special algorithms to make short work of problems that would take a classical computer a long time to work out... if they could ever calculate them at all. Such algorithms would be useful in solving complex mathematical problems, producing hard-to-break security codes, or predicting multiple particle interactions in chemical reactions.

- Quantum Computing: From Research to Reality

Quantum computing is a rapidly developing field, and its future is full of exciting possibilities. However, quantum computing is still in its infancy, and there are many technical and practical challenges to overcome before it can become a mainstream technology. 

These challenges include improving the stability and scalability of quantum hardware, developing better algorithms and error correction techniques, and finding new applications that can take advantage of the unique properties of quantum computing. A few potential directions for future quantum computing are listed below:

• Improved hardware: Developing hardware that can reliably perform quantum computations is one of the main challenges of quantum computing. To mitigate the effects of noise and decoherence, researchers are developing better quantum processors and improving error correction techniques. 
• Applications in chemistry and materials science: By simulating complex chemical reactions and interactions that are difficult or impossible to model with conventional computers, quantum computing may be able to greatly accelerate the discovery of new materials and drugs. 
• Advances in cryptography: Quantum computing has the potential to break many of the encryption algorithms used today to protect sensitive information. However, researchers are also working on developing new quantum-safe encryption methods that are resistant to attacks by quantum computers. 
• Optimization and machine learning: Quantum computing can be used to solve optimization problems that are difficult for classical computers, such as those encountered in logistics and supply chain management. Quantum machine learning can also significantly improve data analysis and pattern recognition. 
• Hybrid Classical-Quantum Computing: Many applications may require a combination of classical and quantum computing for optimal results. Researchers are developing ways to integrate classical and quantum algorithms to take advantage of the strengths of each.

- Quantum States

A quantum state is a state of a system of quantum mechanics. The precise mathematical notion of state depends on what mathematical formalization of quantum mechanics is used.

In quantum physics, a quantum state is a mathematical entity that embodies the knowledge of a quantum system. Quantum mechanics specifies the construction, evolution, and measurement of a quantum state. The result is a quantum mechanical prediction for the system represented by the state. 

Knowledge of the quantum state together with the quantum mechanical rules for the system's evolution in time exhausts all that can be known about a quantum system.

[The University of Chicago]

- Superconducting Qbits

Quantum devices often look very different from their classical counterparts. There is one exception – the central piece of some of the most advanced quantum computers is still a chip. It is not made from silicon but from materials that are superconducting. 

Superconductors are implemented in quantum computing because they possess both near infinite conductivity and near zero resistance.  
Superconducting qubits are among the most promising approaches to building quantum computers. 

At the most basic level, a superconducting qubit is simply a circuit loop with an electrical current traveling around it. That circuit is made up of metals that become superconducting — i.e., able to conduct current without resistance — when cooled below a certain critical temperature.

- Managing Quantum Noise

Quantum noise is a major obstacle to the development of quantum computing. It is a disturbance that can change the outcome of a quantum system and is caused by factors such as magnetic fields, electronic device interference, and qubit interactions. Overcoming this challenge, known as quantum decoherence, is critical to advances in quantum computing, which aims to achieve greater reliability and accuracy. 

Strategies such as error suppression, error mitigation, and quantum error correction (QEC) have been designed to reduce the impact of noise on qubits, thereby improving calculation accuracy. 

These advances are critical to achieving quantum supremacy—the ability of quantum computers to solve problems more efficiently than conventional computers.