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Tera-mode of Spatiotemporal N00N States

Xiaoqin Gao, Yingwen Zhang, Alessio D’Errico, Khabat Heshami, Ebrahim Karimi

Published Jul 6, 2021• 0 citations
OpenAlex

Abstract

Two-photon interference is widely used in quantum information processing, e.g., state engineering and designing quantum gates, as well as in quantum sensing and metrology. This includes the generation and characterization of N00N states, which provide a phase measurement sensitivity that is beyond the shot-noise limit. There have been numerous efforts in generating N00N states with a photon number higher than 2, since their measurement sensitivity increases with N. Both photon number state and modal (temporal, spectral, and spatial) properties of light offer advantages in sensing, where the latter is achieved through mode-multiplexed measurements. Here, we experimentally demonstrate, with the aid of a recently developed photon-detection technology, measurement and characterization of up to tera-mode spatiotemporal correlations in two-photon interference and use it to generate high-dimensional two-photon N00N-states, which can be advantageous for multiphase estimation. We observe a high bi-photon interference and coalescence visibility of $\sim64\%$ and $\sim88\%$ for a tera ($10^{12}$) and 0.2 tera ($2\times 10^{11}$) spatiotemporal modes, respectively. These results open up a route for practical applications of using the spatiotemporal degrees of freedom in two-photon interference, and in particular, for quantum sensing and communication.

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Two-photon interference is widely used in quantum information processing, e.g., state engineering and designing quantum gates, as well as in quantum sensing and metrology. This includes the generation and characterization of N00N states, which provide a phase measurement sensitivity that is beyond the shot-noise limit. There have been numerous efforts in generating N00N states with a photon number higher than 2, since their measurement sensitivity increases with N. Both photon number state and modal (temporal, spectral, and spatial) properties of light offer advantages in sensing, where the latter is achieved through mode-multiplexed measurements. Here, we experimentally demonstrate, with the aid of a recently developed photon-detection technology, measurement and characterization of up to tera-mode spatiotemporal correlations in two-photon interference and use it to generate high-dimensional two-photon N00N-states, which can be advantageous for multiphase estimation. We observe a high bi-photon interference and coalescence visibility of ∼64%\sim64\%∼64% and ∼88%\sim88\%∼88% for a tera (101210^{12}1012) and 0.2 tera (2×10112\times 10^{11}2×1011) spatiotemporal modes, respectively. These results open up a route for practical applications of using the spatiotemporal degrees of freedom in two-photon interference, and in particular, for quantum sensing and communication.
The Hong-Ou-Mandel interference effect lies at the heart of many emerging quantum technologies whose performance can be significantly enhanced with increasing numbers of entangled modes one could measure and thus utilize. Photon pairs generated through the process of spontaneous parametric down conversion are known to be entangled in a vast number of modes in the various degrees of freedom (DOF) the photons possess such as time, energy, and momentum, etc. Due to limitations in detection technology and techniques, often only one such DOFs can be effectively measured at a time, resulting in much lost potential. Here, we experimentally demonstrate, with the aid of a time tagging camera, high speed measurement and characterization of two-photon interference. With a data acquisition time of only a few seconds, we observe a bi-photon interference and coalescence visibility of ∼64% with potentially up to ∼2 × 103 spatial modes. These results open up a route for practical applications of using the high dimensionality of spatiotemporal DOF in two-photon interference, and in particular, for quantum sensing and communication.
The control of photons represents a pillar for our modern technological society. The emerging field of quantum photonics exploits quantum properties of light to dramatically improve the performance of protocols for metrology, communication and information processing. However, modern applications exploit very little of the enormous potential of the photon. Unfortunately, the challenges involved in the preparation and characterization of photonic states with multiple particles, impose practical limitations to realistic quantum technologies. In this talk, I will report on our recent results on the preparation, manipulation and characterization of quantum states with multiple photons. I will describe how the manipulation of the quantum electromagnetic fluctuations of a pair of vacuum states leads to a novel family of quantum-correlated multiphoton states with tunable mean photon numbers and degrees of correlations. Our technique relies on the use of conditional measurements to engineer the vacuum and consequently the excitation mode of the field through the simultaneous subtraction of photons from two-mode squeezed vacuum states. In addition, I will describe the potential of combing these states with photon number resolving measurements for quantum phase estimation. The last part of my talk will be devoted to discuss our recent technique that allowed us to utilize compressive sensing to demonstrate measurement of high-dimensional states, that describe telecom photon pairs in the spatial and spectral degrees of freedom, with 12 billions of elements using only a small fraction of measurements.
Path-entangled multi-photon states allow optical phase-sensing beyond the shot-noise limit, provided that an efficient parity measurement can be implemented. Realizing this experimentally is technologically demanding, as it requires coincident single-photon detection proportional to the number of photons involved, which represents a severe challenge for achieving a practical quantum advantage over classical methods. Here, we exploit advanced quantum state engineering based on superposing two photon-pair creation events to realize a new approach that bypasses this issue. In particular, optical phase shifts are probed with a two-photon quantum state whose information is subsequently effectively transferred to a single-photon state. Notably, without any multiphoton detection, we infer phase shifts by measuring the average intensity of the single-photon beam on a photodiode, in analogy to standard classical measurements. Importantly, our approach maintains the quantum advantage: twice as many interference fringes are observed for the same phase shift, corresponding to N = 2 path-entangled photons. Our results demonstrate that the advantages of quantum-enhanced phase sensing can be fully exploited in standard intensity measurements, paving the way toward resource-efficient and practical quantum optical metrology.
Multi-photon entangled states of light such as N00N (N is the photon number) and squeezed states are routinely used in quantum metrological experiments. Spatially structuring these quantum optical states improves the sensitivity and enhances resolution by using the high dimensional spatial degree of freedom. However, progress in quantum structured light mainly focused on either increasing the number of photons, or increasing the mode numbers, separately [1]. The reason is that generating high (mode number>> 10) dimensional structured light states is usually a lossy process that degrades multi-photon states of light.
Quantum states of light, such as squeezed states or entangled states, can be used to make measurements (metrology), produce images, and sense objects with a precision that far exceeds what is possible classically, and also exceeds what was once thought to be possible quantum mechanically. The primary idea is to exploit quantum effects to beat the shot-noise limit in metrology and the Rayleigh diffraction limit in imaging and sensing. Quantum optical metrology has received a boost in recent years with an influx of ideas from the rapidly evolving field of optical quantum information processing. Both areas of research exploit the creation and manipulation of quantum-entangled states of light. We will review some of the recent theoretical and experimental advances in this exciting new field of quantum optical metrology, focusing on examples that exploit a particular two-mode entangled photon state – the High-N00N state.
Spatial interference of quantum mechanical particles exhibits a fundamental feature of quantum mechanics. A two-mode entangled state of N particles known as N00N state can give rise to non-classical interference. We report the first experimental observation of a three-photon N00N state exhibiting Young's double-slit type spatial quantum interference. Compared to a single-photon state, the three-photon entangled state generates interference fringes that are three times denser. Moreover, its interference visibility of 0.49 ± 0.09 is well above the limit of 0.1 for spatial super-resolution of classical origin. The demonstration of spatial quantum interference by a N00N state composed of more than two photons represents an important step towards applying quantum entanglement to technologies such as lithography and imaging.