We propose a photonic platform for simulating arbitrary single-qubit open-system dynamics using a single photon in an open Mach-Zehnder interferometer. A birefringent quartz plate induces a coupling between the polarization and frequency degrees of freedom. By treating the latter as an effective environment, we analytically derive the reduced polarization dynamics. We show that the resulting evolution is characterized by a controllable interplay between populations and coherence, instead of the usual dephasing caused by quartz plates. By adjusting the photon frequency distribution and interferometric parameters, we demonstrate that target single-qubit states can be efficiently reproduced through a tunable optical protocol expected to work under accessible experimental conditions. The simulator is benchmarked against paradigmatic open-system evolutions, including depolarization and non-Markovian dynamics, achieving high accuracy. Our results establish polarization-frequency engineered photonic interferometers as a versatile protocol for simulation of open quantum systems.
We propose a photonic platform for simulating arbitrary single-qubit open-system dynamics using a single photon in an open Mach-Zehnder interferometer. A birefringent quartz plate induces a coupling between the polarization and frequency degrees of freedom. By treating the latter as an effective environment, we analytically derive the reduced polarization dynamics. We show that the resulting evolution is characterized by a controllable interplay between populations and coherence, instead of the usual dephasing caused by quartz plates. By adjusting the photon frequency distribution and interferometric parameters, we demonstrate that target single-qubit states can be efficiently reproduced through a tunable optical protocol expected to work under accessible experimental conditions. The simulator is benchmarked against paradigmatic open-system evolutions, including depolarization and non-Markovian dynamics, achieving high accuracy. Our results establish polarization-frequency engineered photonic interferometers as a versatile protocol for simulation of open quantum systems.
The evolution of a quantum system interacting with an environment can be described as a unitary process acting on both the system and the environment. In this framework, the system's evolution can be predicted by tracing out the environmental degrees of freedom. Here, we establish a precise mapping between the global unitary dynamics and the quantum operation involving the system, wherein the system is a single qubit, and the environment is modeled as a discrete lattice space. This approach enables the implementation of arbitrary noise operations on single-polarization qubits using a minimal set of three liquid-crystal metasurfaces, whose transverse distribution of the optic axes can be patterned to reproduce the target process. We experimentally validate this method by simulating common noise processes, such as phase errors and depolarization. Besides providing a practical solution for quantum state purification, this work demonstrates a versatile approach for the simulation of open qubit dynamics, with potential implications for quantum error correction and environment-induced quantum phase transitions.
We combine the dynamics of open quantum systems with interferometry and interference, introducing the concept of an open system interferometer. By considering a single photon in a Mach-Zehnder interferometer, where the polarization (open system) and frequency (environment) of the photon interact, we theoretically show that inside the interferometer, pathwise polarization dephasing dynamics is Markovian while the joint dynamics displays non-Markovian features. Outside the interferometer and due to interference, the open system displays rich dynamical features with distinct alternatives: only one path displays non-Markovian memory effects, both paths individually display them, or no memory effects appear at all. The scheme allows one to (1) probe the optical path difference inside the interferometer by studying pathwise non-Markovianity outside the interferometer, and (2) introduce pathwise dissipative features for the open system dynamics even though the system-environment interaction itself contains only dephasing. Due to the path dependencies, our results are tightly connected to quantum erasure. In general, our results open up alternative ways to control open system dynamics and for fundamental studies of quantum physics.
We present a theoretical scheme and its experimental proof of principle for an open quantum system undergoing Markovian and non-Markovian evolutions. We exhibit these two regimes by diagnosing them with the relative entropy of coherence of two polarization qubits playing the roles of system and ancilla. These are initially prepared in a polarization maximally entangled state of a photon pair produced by spontaneous parametric down-conversion. We induce Markovian and non-Markovian regimes in the system's dynamics with the help of two auxiliary qubits, experimentally implemented by optical paths in a layout of Sagnac and Mach-Zehnder interferometers. We replicate system-environment interactions by means of an amplitude damping channel and a suitably designed inversion of it. In our scheme, one needs only two experimentally accessible parameters to achieve Markovian and non-Markovian regimes.
Quantum simulation is one of the core areas in the development of quantum technologies. Among the various simulation platforms, integrated waveguides have proven to be a powerful and versatile tool. One important aspect of quantum simulation is the analysis of open quantum systems. In most practical applications it is in fact essential to understand and control the dynamics between the quantum system and its environment. Typical effects of interest for example involve decoherence or memory effects, which lead to non-Markovian behavior.
In this work we establish integrated waveguides as a tool for the simulation of open quantum systems. Using polarization as well as a photon's path degree of freedom, we implement the coupling of a qubit with a low dimensional discrete environment. Based on a measure of non-Markovianity, we define and quantify specific types of information and information transfer between system and environment. Experimentally we implement and verify non-Markovian evolution in an optical waveguide array and analyze types of information flow between system and environment realizable through integrated photonics.
Engineering, controlling, and simulating quantum dynamics is a strenuous task. However, these techniques are crucial to develop quantum technologies, preserve quantum properties, and engineer decoherence. Earlier results have demonstrated reservoir engineering, construction of a quantum simulator for Markovian open systems, and controlled transition from Markovian to non-Markovian regime. Dephasing is an ubiquitous mechanism to degrade the performance of quantum computers. However, all-purpose quantum simulator for generic dephasing is still missing. Here, we demonstrate full experimental control of dephasing allowing us to implement arbitrary decoherence dynamics of a qubit. As examples, we use a photon to simulate the dynamics of a qubit coupled to an Ising chain in a transverse field and also demonstrate a simulation of nonpositive dynamical map. Our platform opens the possibility to simulate dephasing of any physical system and study fundamental questions on open quantum systems.
Quantum optics plays a crucial role in developing quantum computers on different platforms. In photonics, precise control over light's degrees of freedom, including discrete variables (polarization, photon number, orbital angular momentum) and continuous variables (phase, amplitude quadratures, frequency), is fundamental. Our model manipulates photonic systems to encode and process quantum information via the photon's spatial degree of freedom, employing polarization as an auxiliary qubit. We propose a programmable photonic circuit that simulates quantum channels, including phase-damping, amplitude-damping, and bit-flip channels, through adjustable interferometric parameters. Furthermore, the interferometer extends to complex channels, such as the squeezed generalized amplitude damping. This work contributes to advancing quantum simulation techniques and serves as a foundation for exploring quantum computing applications, while highlighting pathways for their practical implementation.