All-optical design for inherently energy-conserving reversible gates and circuits

SWAP and Fredkin gates for OAM optical beams via the sandwich of anisotropic optical fibers

We study the propagation of circularly-polarized optical vortices of higher order topological charges ℓ ≥ 2 in a sandwich of multihelical - anisotropic - multihelical fibers on the basis of the Jones formalism for modes with orbital angular momentum. We demonstrate that such a system can operate as the all - fiber two - bit SWAP as well as universal tree - bit controlled-SWAP (Fredkin) gates over states of optical vortices, in which the mode radial number carries the control bit, while circular polarization and topological charge are the controlled bits.

A Logically Reversible Double Feynman Gate with Molecular Engineered Bacteria Arranged in an Artificial Neural Network-Type Architecture

Reversible logic gates are the key components of reversible computing that map inputs and outputs in a certain one-to-one pattern so that the output signals can reveal the pattern of the input signals. One of the main research foci of reversible computing is the implementation of basic reversible gates by various modalities. Though true thermodynamic reversibility cannot be attained within living cells, the high energy efficiency of biological reactions inspires the implementation of reversible computation in living cells. The implementation of synthetic genetic circuits is mostly based on conventional irreversible computing, and the implementation of logical reversibility in living cells is rare. Here, we constructed a 3-input-3-output synthetic genetic reversible double Feynman logic gate with a population of genetically engineered E. coli cells. Instead of following hierarchical electronic design principles, we adapted the concept of artificial neural networks (ANN) and built a single-layer artificial network-type architecture with five different engineered bacteria, named bactoneurons. We used three extracellular chemicals as input signals and the expression of three fluorescence proteins as the output signals. The cellular devices, which combine the input chemical signals linearly and pass them through a nonlinear activation function and represent specific bactoneurons, were built by designing and creating small synthetic genetic networks inside E. coli. The weights of each of the inputs and biases of individual bactoneurons in the bacterial ANN were adjusted by optimizing the synthetic genetic networks. When arranging the five bactoneurons through an ANN-type architecture, the system generated a double Feynman gate function at the population level. To our knowledge, this is the first reversible double Feynman gate realization with living cells. This work may have significance in development of biocomputer technology, reversible computation, ANN wetware, and synthetic biology.

Multifunctional and wavelength division multiplexing all-optical logic gates based on four-port metal-insulator-metal waveguides coupled with a ring resonator

In the past few years, designing multifunctional all-optical logic devices has attracted more and more attention in integrated optical computing. We report a metal-insulator-metal based four-port all-optical logic gate device containing two parallel straight waveguides and a ring resonator. We employ the scattering matrix method to analyze the coupling mechanisms of the hybrid waveguide and adopt the finite-difference time-domain method to design four fundamental logic functions of AND, OR, XOR, and NOT based on the all-optical coherent control of the four-port system under three symmetrically incident conditions. We demonstrate that these logic functions can be freely modulated by changing the phase difference of the input light at two resonant wavelengths or in a broad band. The logic gate device proposed shows a simple structure with multiple functions, multiple channels, and convenience in fabrication, and can be applied in parallel optical computing based on wavelength division multiplexing technology.

Synthetic Genetic Reversible Feynman Gate in a Single E. coli Cell and Its Application in Bacterial to Mammalian Cell Information Transfer

Reversible computing is a nonconventional form of computing where the inputs and outputs are mapped in a unique one-to-one fashion. Reversible logic gates in single living cells have not been demonstrated. Here, we constructed a synthetic genetic reversible Feynman gate in single E. coli cells, and the input-output relations were measured in a clonal population. The inputs were extracellular chemicals, isopropyl β-d-1-thiogalactopyranoside (IPTG), and anhydrotetracycline (aTc), and the outputs were two fluorescence proteins. We developed a simple mathematical model and simulation to capture the essential features of the circuit and experimentally demonstrated that the behavior of the circuit was ultrasensitive and predictive. We showed an application by creating an intercellular Feynman gate, where input information from bacteria was computed and transferred to HeLa cells through shRNAs delivery and the output signals were observed as silencing of native AKT1 and CTNNB1 genes. The introduction of reversible logics in synthetic biology is new, and given that one-to-one input-output mapping, such reversible genetic systems might have applications in sensing, diagnostics, cellular computing, and synthetic biology.

Quantum-inspired Fredkin gate based on spatial modes of light

Insights gained from quantum physics can inspire novel classical technologies. These quantum-inspired technologies are protocols that aim at mimicking particular features of quantum algorithms. They are generally easier to implement and make use of intense beams. Here we demonstrate in a proof-of-concept experiment a quantum-inspired protocol based on the idea of quantum fingerprinting (Phys. Rev. Lett. 87, 167902, 2001).The carriers of information are optical beams with orbital angular momentum (OAM). These beams allow the implementation of a Fredkin gate or polarization-controlled SWAP operation that exchanges data encoded on beams with different OAM. We measure the degree of similarity between waveforms and strings of bits without unveiling the information content of the data.