Quantum computers have been proposed to solve significant problems such as discovering new drugs, optimizing financial portfolios, and implementing new artificial intelligence applications. However, Xavier Waintal from Université Grenoble Alpes argues that even simple tasks like multiplying 3 by 5 are beyond existing quantum hardware. An article by Xavier named “The Quantum House of Cards” was published in ArXiv on 29th December 2023.
He discusses the challenges that need to be overcome for quantum computers to fulfill their potential, including the need for quantum error correction. Waintal is skeptical about the prospects of quantum computing but acknowledges the ongoing revolution in experimental quantum physics.
Quantum Computing: A Quantum House of Cards?
Quantum computers have been proposed as solutions to a variety of complex problems, from drug discovery to financial portfolio optimization. However, Xavier Waintal from Université Grenoble Alpes, argues that the current state of quantum computing technology is far from being able to fulfill these promises.
The Challenges of Quantum Computing
Waintal compares the current state of quantum computing to a house of cards, highlighting its lack of robustness. Quantum technologies rely on subtle, volatile, transient physical effects and are constantly battling against the second law of thermodynamics. The author argues that the main challenge in quantum computing is the exponential decay of fidelity due to decoherence, which is the loss of information from a system into the environment.
“I am very skeptical that a quantum computer will ever solve serious problems. When I express these doubts to colleagues, the answer I mostly get is a variation along the line of the following: “You’re right, it looks difficult. But when the first transistor was built, one could never have foreseen the computer revolution, internet, smartphones, AI… Quantum bits might be the new transistor.”
Xavier Waintal
The Limitations of Quantum Algorithms
Despite the hype around quantum computing, there are only a handful of quantum algorithms currently in existence. These algorithms, such as Shor’s and Grover’s, are highly specialized and require a high level of precision to execute correctly. Waintal argues that the precision required for these algorithms to work is currently beyond the capabilities of existing quantum hardware.
The Reality of Quantum Applications
While quantum computing has been touted as a solution to a wide range of problems, Waintal argues that the reality is much more limited. Quantum computers deliver very few bits of information, making them suitable only for highly specific applications. They will not replace classical computers but may complement them in certain areas.
The Future of Quantum Computing
Despite his skepticism, Waintal acknowledges the ongoing revolution in quantum sciences. He suggests that while the journey towards quantum computing may be more important than the intended destination, it may still be too early to foresee the applications of this technology. He also highlights the potential of quantum simulations and analog systems, which may provide important information about less controllable systems such as new materials.
The Role of Classical Algorithms
Waintal concludes by suggesting that some of the key applications proposed for quantum computing may be achievable through classical methods. He points out that many problems initially thought to be exponentially difficult have been solved in polynomial time with numerical techniques. He suggests that the real goal of physics is not to calculate specific numbers, but to unveil the hidden structures that can be exploited to speed up calculations.
“I have tried to convey the idea that, perhaps, quantum computing as it has been envisioned so far is simply too difficult to happen. However, it remains that there is a genuine revolution that is going on in quantum sciences. We are exploring frontiers that were thought impossible only a few decades ago. Perhaps this is one of those cases where the journey is more important than the intended destination and that it is simply too early to foresee the applications. After all, if we could not foresee the internet when we invented the transistor, perhaps we’re not better off now?”
Xavier Waintal
Summary
Quantum computers have been proposed to solve complex problems such as drug discovery and encryption protocols, but currently, even simple tasks like multiplying 3 by 5 are beyond their capabilities. Despite the ongoing revolution in quantum sciences, the author suggests that the challenges of building a quantum computer, including the need for ultra-low error levels and high precision, may be too difficult to overcome, and that some of the tasks envisioned for quantum computers may eventually be achieved by classical algorithms on classical hardware.
“Also, it strikes me that some of the key applications that have been put forward for quantum computing (e.g. for solving chemistry problems or correlated matter) are slowly coming into the scope of classical methods.”
Xavier Waintal
- The article is written by Xavier Waintal from Université Grenoble Alpes, PHELIQS, CEA, Grenoble INP, IRIG, Grenoble, France.
- Quantum computers have been proposed to solve important problems such as discovering new drugs, new catalysts for fertilizer production, breaking encryption protocols, optimizing financial portfolios, or implementing new artificial intelligence applications.
- However, a simple task such as multiplying 3 by 5 is beyond existing quantum hardware.
- The article discusses the challenges that need to be solved for quantum computers to live up to their promises, including the stack of technologies required to build a quantum computer and the crucial intermediate layer of quantum error correction.
- The author expresses skepticism about the prospects of quantum computing but acknowledges the ongoing revolution in experimental quantum physics.
- The article highlights the difficulties of achieving the necessary precision for quantum algorithms to work and the limited number of applications where quantum computers could have a genuine advantage.
- The author suggests that some of the key applications proposed for quantum computing are slowly coming into the scope of classical methods.
- The article concludes by suggesting that the real goal of physics is not to calculate specific numbers but to unveil hidden structures.
