An official website of the United States government
In the realm of quantum information processing, harnessing high-dimensional photonic systems provides a pathway to overcome limitations of traditional two-level systems. Orbital angular momentum (OAM) of light has emerged as a powerful tool for creating and manipulating high-dimensional entanglement, promising increased information capacity and enhanced security in quantum communication protocols. However, conventional methods like spontaneous parametric downconversion encounter challenges due to non-uniform production rates of Laguerre–Gaussian modes. This study explores the potential of spontaneous four-wave mixing in ring-core fibers (RCFs) as a viable platform for generating OAM photon pairs with tailored spectral and spatial properties. We show that by controlling the topological charge of pump photons, correlated, uncorrelated, and anti-correlated photon pairs can be engineered across arbitrary spectral ranges, essential for diverse quantum applications. Experimental noise characterization of the RCF-based source demonstrates a high coincidence-to-accidental ratio exceeding 4000, and a low heralded second-order correlation function (gH(2)<0.005), which confirms its operation well into the single-photon regime. This work demonstrates the potential of RCFs as a versatile platform for generating structured photon pairs, paving the way for future high-dimensional quantum communication and information processing applications.
more »
« less
Growing Quantum Communication Capacity with Spatial Modes of Optical Fiber
Quantum communication links and networks are needed for secure information exchange and for interconnecting future quantum computers. However, their capacity decreases exponentially with distance due to the effect of fiber attenuation that cannot be undone by amplification (although quantum repeaters are an active area of research, they are almost as hard to build as quantum computers). Hence, the only way to increase the quantum communication capacity is by employing more degrees of freedom (optical modes) over which this information can be encoded and transmitted. While frequency (WDM), temporal, and polarization modes have already been exploited for this purpose, the use of many spatial modes has only recently become possible owing to the development of low-loss few-mode fibers (FMFs). This talk will present the work of Prof. M. Vasilyev’s research group on the development of two key enablers of quantum communication over spatial modes of FMFs: 1) generator of spatially-entangled photon pairs and 2) receiver sub-system that can perform projective measurements that alternate between two sets of mutually unbiased bases in a given spatial mode space (this sub-system can also perform dynamically reconfigurable de-multiplexing of spatial modes of the FMF). Both of the above devices / sub-systems are based on the spatial-mode-selective quantum frequency conversion process, implemented in a medium with either second-order nonlinearity (multimode lithium niobate waveguide) or third-order nonlinearity (custom-made FMF). The talk will introduce the principles of their operation, as well as the recent experimental results obtained in both media.
more »
« less
- PAR ID:
- 10385162
- Date Published:
- Journal Name:
- IEEE MetroCon conference, Fort Worth, TX, November 3, 2021
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract The ability to engineer the spatial wavefunction of photons has enabled a variety of quantum protocols for communication, sensing, and information processing. These protocols exploit the high dimensionality of structured light enabling the encoding of multiple bits of information in a single photon, the measurement of small physical parameters, and the achievement of unprecedented levels of security in schemes for cryptography. Unfortunately, the potential of structured light has been restrained to free-space platforms in which the spatial profile of photons is preserved. Here, we make an important step forward to using structured light for fiber optical communication. We introduce a classical encryption protocol in which the propagation of high-dimensional spatial modes in multimode fibers is used as a natural mechanism for encryption. This provides a secure communication channel for data transmission. The information encoded in spatial modes is retrieved using artificial neural networks, which are trained from the intensity distributions of experimentally detected spatial modes. Our on-fiber communication platform allows us to use single spatial modes for information encoding as well as the high-dimensional superposition modes for bit-by-bit and byte-by-byte encoding respectively. This protocol enables one to recover messages and images with almost perfect accuracy. Our classical smart protocol for high-dimensional encryption in optical fibers provides a platform that can be adapted to address increased per-photon information capacity at the quantum level, while maintaining the fidelity of information transfer. This is key for quantum technologies relying on structured fields of light, particularly those that are challenged by free-space propagation.more » « less
-
Gilbert, Seth (Ed.)Quantum computing hardware is improving in robustness, but individual computers still have small number of qubits (for storing quantum information). Computations needing a large number of qubits can only be performed by distributing them over a network of smaller quantum computers. In this paper, we consider the problem of distributing a quantum computation, represented as a quantum circuit, over a homogeneous network of quantum computers, minimizing the number of communication operations needed to complete every step of the computation. We propose a two-step solution: dividing the given circuit’s qubits among the computers in the network, and scheduling communication operations, called migrations, to share quantum information among the computers to ensure that every operation can be performed locally. While the first step is an intractable problem, we present a polynomial-time solution for the second step in a special setting, and a O(log n)-approximate solution in the general setting. We provide empirical results which show that our two-step solution outperforms existing heuristic for this problem by a significant margin (up to 90%, in some cases).more » « less
-
Abstract Implementing microelectromechanical system (MEMS) resonators calls for detailed microscopic understanding of the devices, such as energy dissipation channels, spurious modes, and imperfections from microfabrication. Here, we report the nanoscale imaging of a freestanding super-high-frequency (3 – 30 GHz) lateral overtone bulk acoustic resonator with unprecedented spatial resolution and displacement sensitivity. Using transmission-mode microwave impedance microscopy, we have visualized mode profiles of individual overtones and analyzed higher-order transverse spurious modes and anchor loss. The integrated TMIM signals are in good agreement with the stored mechanical energy in the resonator. Quantitative analysis with finite-element modeling shows that the noise floor is equivalent to an in-plane displacement of 10 fm/√Hz at room temperatures, which can be further improved under cryogenic environments. Our work contributes to the design and characterization of MEMS resonators with better performance for telecommunication, sensing, and quantum information science applications.more » « less
-
This article explores the nonlinear vibration of beams with different types of nonlinearities. The beam vibration was modeled using Hamilton’s principle, and the equation of motion was solved using method of multiple time scales. Three models were developed assuming (a) geometric nonlinearity, (b) material nonlinearity and (c) combined geometric and material nonlinearity. The material nonlinearity also included both third and fourth nonlinear elasticity terms. The frequency response equation of these models were further evaluated quantitatively and qualitatively. The models capture the hardening effect, i.e., increase in resonant frequency as a function of forcing amplitude for geometric nonlinearity, and the softening effect, i.e., decrease in resonant frequency for material nonlinearity. The model is applied on the first three bending modes of the cantilever beam. The effect of the fourth-order material nonlinearity was smaller compared to the third-order term in the first mode, whereas it is significantly larger in second and third mode. The combined nonlinearity models shows a discontinuous frequency shift, which was resolved by utilizing a set of transition assumptions. This results in a smooth transition between the material and geometric zones in amplitude. These parametric models allow us to fine tune the nonlinear response of the system by changing the physical properties such as geometry, linear and nonlinear elastic properties.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Conference Paper:
- The DOI is not currently available.
