No Arabic abstract
We propose an optical parallel computation similar to quantum computation that can be realized by introducing pseudorandom phase sequences into classical optical fields with two orthogonal modes. Based on the pseudorandom phase sequences, we first propose a theoretical framework of phase ensemble model referring from the concept of quantum ensemble. Using the ensemble model, we further demonstrate the inseparability of the fields similar to quantum entanglement. It is interesting that a N2^N dimensional Hilbert space spanned by N optical fields is larger than that spanned by N quantum particles. This leads a problem for our scheme that is not the lack of resources but the redundancy of resources. In order to reduce the redundancy, we propose a special sequence permutation mechanism to efficiently imitate certain quantum states, including the product state, Bell states, GHZ state and W state. For better fault tolerance, we further devise each orthogonal mode of optical fields is measured to assign discrete values. Finally, we propose a generalized gate array model to imitate some quantum algorithms, such as Shors algorithm, Grovers algorithm and quantum Fourier algorithm. The research on the optical parallel computation might be important, for it not only has the potential beyond quantum computation, but also provides useful insights into fundamental concepts of quantum mechanics.
We demonstrate that a tensor product structure and optical analogy of quantum entanglement can be obtained by introducing pseudorandom phase sequences into classical fields with two orthogonal modes. Using the classical analogy, we discuss efficient simulation of several typical quantum states, including product state, Bell states, GHZ state, and W state. By performing quadrature demodulation scheme, we propose a sequence permutation mechanism to simulate certain quantum states and a generalized gate array model to simulate quantum algorithm, such as Shors algorithm and Grovers algorithm. The research on classical simulation of quantum states is important, for it not only enables potential beyond quantum computation, but also provides useful insights into fundamental concepts of quantum mechanics.
An effective simulation of quantum entanglement is presented using classical fields modulated with n pseudorandom phase sequences (PPSs) that constitute a n2^n-dimensional Hilbert space with a tensor product structure. Applications to classical fields are examplied by effective simulation of both Bell and GHZ states, and a correlation analysis was performed to characterize the simulation. Results that strictly comply with criteria of quantum entanglement were obtained and the approach was also shown to be applicable to a system consisting of n quantum particles.
We propose a geometric phase gate of two ion qubits that are encoded in two levels linked by an optical dipole-forbidden transition. Compared to hyperfine geometric phase gates mediated by electric dipole transitions, the gate has many interesting properties, such as very low spontaneous emission rates, applicability to magnetic field insensitive states, and use of a co-propagating laser beam geometry. We estimate that current technology allows for infidelities of around 10$^{-4}$.
Quantum information processing (QIP) offers the promise of being able to do things that we cannot do with conventional technology. Here we present a new route for distributed optical QIP, based on generalized quantum non-demolition measurements, providing a unified approach for quantum communication and computing. Interactions between photons are generated using weak non-linearities and intense laser fields--the use of such fields provides for robust distribution of quantum information. Our approach requires only a practical set of resources, and it uses these very efficiently. Thus it promises to be extremely useful for the first quantum technologies, based on scarce resources. Furthermore, in the longer term this approach provides both options and scalability for efficient many-qubit QIP.
The key to optical analogy to a multi-particle quantum system is the scalable property. Optical elds modulated with pseudorandom phase sequences is an interesting solution. By utilizing the properties of pseudorandom sequences, mixing multiple optical elds are distinguished by using coherent detection and correlation analysis that are mature methods in optical communication. In this paper, we utilize the methods to investigate optical analogies to multi-particle quantum states. In order to demonstrate the feasibility, numerical simulations are carried out in the paper, which is helpful to the experimental verication in the future.