Limitations of quantum computing
Quantum computers may have fundamental limits: While theories suggest that these futuristic machines will need millions of qubits to become truly useful, quantum computers may actually reach a limit of around 1,000 qubits.
“We introduce a theory of quantum physics based on the notion that the continuous nature of the quantum mechanical state space approximates something inherently discrete, and we argue that the reason for such discretization is gravity. From this, we predict that quantum computers will never be able to break RSA-encrypted messages in real-world situations, for fundamental, not practical, reasons,” writes Professor Tim Palmer of the University of Oxford.
There has always been much hope, and also much hype, surrounding the seemingly limitless potential of quantum computers, basically because, while in a classical computer information grows linearly with the number of bits, each additional qubit doubles the number of quantum states that a quantum machine can occupy.
Since these states can encode multiple possibilities simultaneously, the entire system appears to become exponentially more powerful with each new qubit.
This is where Professor Palmer’s new theory comes in: This exponential growth is reflected in Hilbert space, an abstract mathematical structure that generalizes the concept of Euclidean space to n dimensions, with each possible state of a system being represented as a point. Thus, the more qubits, the more dimensions this space acquires, and the standard theory assumes that the system can explore this space smoothly and continuously, like an analog island in a digital ocean.
But it might not be quite like that.
[Image: TU Wien] Law of physics
Fundamental limit of quantum computers
Professor Palmer argues that the physical reality behind the exploration of Hilbert space may be far more discrete ( à la quantum mechanics) than theory supposes: There would only be a limited amount of physical information that a system could carry, an amount insufficient to assign fully independent values to each dimension of Hilbert space as it grows.
It follows that, although Hilbert space continues to expand exponentially in theory, the accessible portion of this space becomes increasingly restricted. Quantum states could only occupy a limited and countable set of possibilities. According to Professor Palmer’s estimates, this ceiling would begin to manifest itself around 1,000 qubits, a number that has already been surpassed by some current quantum computing architectures.
Still, it’s worth continuing to invest in quantum computers for other reasons, such as studying physics itself and, who knows, in the future, discovering how to take advantage of their mechanisms for more general purposes.
“If [my theory] is proven, the greatest impact of quantum computers could be in the development of new finite theories that synthesize quantum and gravitational physics, potentially with commercial benefits (albeit for future generations) that surpass those derived solely from quantum mechanics,” the researcher concluded.
Source: www.inovacaotecnologica.com.br
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