Two-way quantum computers (like in Ising model) - are they possible? Could solve general NP problems?

[quantumadmin]

Two-way quantum computers, also known as reversible quantum computers or quantum computers based on the Ising model, refer to a hypothetical model of quantum computing where the time evolution of the quantum system is bidirectional, allowing for both forward and backward computations. In this model, the computation is not limited to a fixed time direction as in standard quantum computing.

The concept of two-way quantum computers is an area of theoretical research, and it is still a topic of ongoing study and exploration. However, it is important to note that reversible computing, which forms the basis for two-way quantum computing, is subject to fundamental limitations.

While two-way quantum computers have intriguing properties, such as the potential for efficient time reversal and the ability to extract more information from quantum states, it is not clear if they can solve general NP (Non-deterministic Polynomial time) problems more efficiently than classical or one-way quantum computers.

The question of whether two-way quantum computers can solve general NP problems efficiently is still an open research question. NP problems are a class of computational problems where a solution can be verified in polynomial time. The central challenge lies in finding an efficient algorithm that can solve NP problems in polynomial time using a two-way quantum computer.

It's important to recognize that quantum computers, regardless of the computational model, are not believed to violate the widely accepted complexity theoretic conjecture known as P ≠ NP. This conjecture implies that there are no polynomial-time algorithms for solving NP-complete problems unless P = NP.

In summary, two-way quantum computers are an area of theoretical research, and their potential capabilities and limitations are still being investigated. While they have interesting properties, their ability to solve general NP problems more efficiently than classical or one-way quantum computers remains an open question