by The quantum advantage is the milestone that the field of quantum computing is working hard towards, where a quantum computer can solve problems that are beyond the reach of the most powerful non-quantum or classical computers.
Quantum refers to the scale of atoms and molecules where the laws of physics as we experience them break down and a series of other, less well-known laws apply. Quantum computers take advantage of these strange behaviors to solve problems.
There are certain types of problems that are impractical for classical computers to solve, such as cracking state-of-the-art encryption algorithms. Research in recent years has shown that quantum computers have the potential to solve some of these problems. If a quantum computer can be built that solves one of these problems, it will have demonstrated a quantum advantage.
I am a physicist who studies quantum information processing and the control of quantum systems. I believe that this frontier of scientific and technological innovation represents not only groundbreaking advances in computing but also represents a broader boom in quantum technology, including significant advances in quantum cryptography and quantum sensing.
The power source of quantum computing
Central to quantum computing is the quantum bit, or qubit. Unlike classical bits, which can only be in states of 0 or 1, a qubit can be in any state containing some combination of 0 and 1. This state is called a quantum superposition which is only 1 or just 0 .With each additional qubit, the number of states that can be represented by the qubits doubles.
This property is often mistaken for the source of the power of quantum computing. Instead, it involves a complex interplay of superimposition, interference and entrapment.
Interference involves manipulating cubes so that their states converge constructively during computations to increase correct solutions and destructively suppress incorrect responses. Constructive interference is what happens when the peaks of two waves – such as sound waves or ocean waves – combine to create a higher peak. Destructive interference is what happens when the crest and trough of a wave collide and cancel each other out. Quantum algorithms, which are few and difficult to devise, determine a sequence of interference patterns that provide the correct answer to a problem.
The entanglement establishes a unique quantum correlation between qubits: One’s state cannot be described independently of the others, no matter how far apart the qubits are. This is what Albert Einstein famously dismissed as “a frighteningly distant act”. Entanglement’s collective behavior, directed through a quantum computer, enables computational speeds not available to classical computers.
Applications of quantum computing
Quantum computing has a range of potential uses where it can outperform classical computers. In cryptography, quantum computers are both an opportunity and a challenge. Most famously, they have the ability to decipher existing encryption algorithms, such as the widely used RSA scheme.
One consequence of this is that today’s encryption protocols need to be re-engineered to resist quantum attacks in the future. This recognition has led to the growing field of post-quantum cryptography. After a long process, the National Institute of Standards and Technology recently selected four quantum-resistant algorithms and has begun the process of preparing them so that organizations around the world can use them in their encryption technology.
In addition, quantum computing can greatly accelerate quantum simulation: the ability to predict the outcome of experiments operating in the quantum field. The famous physicist Richard Feynman saw this possibility more than 40 years ago. Quantum simulation offers the potential for significant advances in chemistry and materials science, helping areas such as modeling complex molecular structures for drug discovery and enabling the discovery or creation of materials with novel properties.
Another use of quantum information technology is quantum sensing: detecting and measuring physical properties such as electromagnetic energy, gravity, pressure and temperature with greater sensitivity and accuracy than non-quantum instruments. Quantum sensing has many applications in areas such as environmental monitoring, geological exploration, medical imaging and surveillance.
Initiatives such as the development of a quantum internet that interconnects quantum computers are critical steps in bridging the worlds of quantum and classical computing. This network could be secured using quantum cryptographic protocols such as quantum key distribution, which enable ultra-secure communication channels that are immune to computational attacks – including those using quantum computers.
Despite a growing set of applications for quantum computing, the development of new algorithms that make full use of the quantum advantage – especially in machine learning – is a critical area of ongoing research.
Stay consistent and overcome errors
The field of quantum computing faces significant hurdles in hardware and software development. Quantum computers are very sensitive to any unintended interactions with their environments. This leads to the phenomenon of decoherence, where qubits quickly degrade to a classical 0 or 1 bit state.
Building large-scale quantum computing systems capable of fulfilling the promise of quantum speeds requires decoherence. The key is to develop effective methods for suppressing and correcting quantum errors, an area on which my own research is focused.
In solving these challenges, many quantum hardware and software startup companies have emerged alongside established players in the technology industry such as Google and IBM. This interest in the industry, combined with significant investment from governments around the world, underscores a common recognition of the transformative potential of quantum technology. These initiatives foster a rich ecosystem where academia and industry work together, accelerating progress in the field.
Quantum advantage emerging
Quantum computing may one day be as disruptive as the advent of next generation AI. Currently, the development of quantum computing technology is at a critical point. On the one hand, the field has already shown early signs of achieving a narrow specialized quantum advantage. Researchers at Google and later a team of researchers in China demonstrated a quantum advantage in generating a list of random numbers with certain properties. My research team demonstrated quantum speed for a random number guessing game.
On the other hand, there is a tangible risk of entering a “quantum winter,” a period of reduced investment if practical results do not materialize soon.
While the technology industry is working to achieve quantum advantage in early products and services, academic research is still focused on investigating the fundamental principles that underpin this new science and technology. This ongoing basic research, fueled by enthusiastic cadres of new and bright students of the kind I meet almost every day, ensures that the field will continue to advance.
This article is republished from The Conversation, a non-profit, independent news organization that brings you reliable facts and analysis to help you make sense of our complex world. The Chat is trusted news from experts. Try our free newsletters.
It was written by: Daniel Lidar, University of Southern California.
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Daniel Lidar receives funding from NSF, DARPA, ARO, and DOE.
