Deterministic Hyperparallel Control Gates with Weak Kerr Effects

Abstract

By harnessing weak cross‐Kerr nonlinearities, it proposes two deterministic hyperparallel quantum control gates, including the hyperparallel controlled‐NOT (hyper‐CNOT) gate and hyperparallel Fredkin (hyper‐Fredkin) gate for photonic systems in the polarization and spatial degrees of freedom (DoFs), which are composed of two procedures for the implementations of the first polarized control (CNOT and Fredkin) gates and the second spatial control (CNOT and Fredkin) ones in turn. Moreover, compared with the two two‐photon CNOT gates (three‐photon Fredkin gates) in one DoF, the hyper‐CNOT (hyper‐Fredkin) gate is provided with more straightforward quantum circuits, lower computational costs of resource overhead (without the assistance of single photons or entangled states), less cross‐Kerr nonlinear interactions between three photons and the coherent states, and reduces the effect caused by photon‐loss noise. The success probabilities of two quantum control gates are approximated unit by performing the corresponding classical feed‐forward operations based on the different measuring outcomes of the X‐homodyne detectors to be aimed at the coherent states, and they are robust against the photon loss as well, which are feasible with the current technology and convenient in practical applications.

Complete analysis of hyperentangled Bell state in three degrees of freedom using Kerr effect and self-assisted mechanism

“…As a counterintuitive phenomenon in the physical world, quantum entanglement is the core resource that enables quantum information technologies, such as quantum teleportation [1], quantum dense coding [2], entanglement swapping [3], quantum imaging [4], and other such tasks. A quantum system simultaneously entangled in more than one degree of freedom (DOF) is known as hyperentanglement [5], which has been widely exploited for high-capacity quantum computation and quantum communication [6][7][8][9][10][11][12]. One of the most important applications of hyperentanglement is that it can be used for the complete Bell state analysis (BSA) [13][14][15].…”

Simplified entanglement swapping protocol for the quantum Internet

“…This is the reason why, even today, the intrinsic springs of what, without a doubt, constitutes the most interesting and useful phenomenon in physics, i.e., entanglement, are unknown in all its magnitude. However, even with incomplete knowledge of it, the twenty-first century has become the moment of the birth of the so-called quantum information science 6 , of which quantum computation 7 – 11 , and quantum communications 12 – 15 represent the most promising verticals, both having entanglement as an essential tool for their development. The advances produced in this area intrinsically imply small and important steps, due to the need to avoid a certain number of obstacles grouped in a family of no-go theorems 6 , of which the most conspicuous is without a doubt the no-cloning theorem 16 .…”

“…The answer is very simple, the security that the quantum version of the internet will offer using the laws of quantum mechanics 5 to preserve the integrity and privacy of the information. This attribute is what will make the difference between both versions of the Internet, given that quantum cryptography protocols 42 , 43 are the only ones that will be prepared to resist future attacks by quantum computers 6 – 11 , which use, for example, the famous Shor’s algorithm 44 , which allows factoring an integer, the basis of the cryptographic algorithm of Rivest, Shamir, and Adleman (RSA) 45 , in polynomial time.…”

Nonlinear Schrödinger Equation for Integrated Photonics

“…The nonlinear Schrödinger (NLS) equation has been a fundamental tool in photonics for decades [1], offering insights into dispersion and the behavior of light in nonlinear optical media. Its applications, spanning optical communications [2], frequency metrology [3], spectroscopy [4], ultrafast science [5], and quantum optics [6,7], underscore its paramount importance in modern optics. Today, the NLS equation is indispensable for modeling devices like all-optical switches [8,9] and optical parametric oscillation (OPO) [10,11].…”