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Measuring on-chip distributable and unconditional entanglement at microwave frequencies

F. Mallet, Hsiang‐Sheng Ku, William Kindel +6 more

Bulletin of the American Physical SocietyMar 22, 20110 citations

Quantifying distributable and unconditional entanglement at microwave frequencies

Hsiang‐Sheng Ku, William Kindel, Scott Glancy +5 more

Bulletin of the American Physical SocietyMar 2, 20120 citations

Ultra-broadband near-field Josephson microwave microscopy

Ping Zhang, Yang-Yang Lyu, Jingjing Lv +15 more

Advanced microwave technologies constitute the foundation of a wide range of modern sciences, including microwave integrated circuits, quantum computing, microwave photonics, spintronics, etc. To facilitate the design of chip-based microwave devices, there is an increasing demand for state-of-the-art microscopic techniques that are capable of characterizing near-field microwave distribution and performance. In this work, we integrate Josephson junctions onto a nanosized quartz tip, forming a highly sensitive microwave mixer on-tip. This allows us to conduct spectroscopic imaging of near-field microwave distributions with high spatial resolution. By leveraging its microwave-sensitive characteristics, our Josephson microscopy achieves a broad detecting bandwidth of ≤200 GHz, as well as remarkable frequency and intensity resolutions. Near-field characterizations of microwave circuits are also conducted to demonstrate the capabilities of Josephson microscopy. Our work emphasizes the benefits of utilizing Josephson microscopy as a real-time, non-destructive technique to advance integrated microwave devices.Advanced microwave technologies constitute the foundation of a wide range of modern sciences, including microwave integrated circuits, quantum computing, microwave photonics, spintronics, etc. To facilitate the design of chip-based microwave devices, there is an increasing demand for state-of-the-art microscopic techniques that are capable of characterizing near-field microwave distribution and performance. In this work, we integrate Josephson junctions onto a nanosized quartz tip, forming a highly sensitive microwave mixer on-tip. This allows us to conduct spectroscopic imaging of near-field microwave distributions with high spatial resolution. By leveraging its microwave-sensitive characteristics, our Josephson microscopy achieves a broad detecting bandwidth of ≤200 GHz, as well as remarkable frequency and intensity resolutions. Near-field characterizations of microwave circuits are also conducted to demonstrate the capabilities of Josephson microscopy. Our work emphasizes the benefits of utilizing Josephson microscopy as a real-time, non-destructive technique to advance integrated microwave devices.

arXiv:2401.12545National Science ReviewSep 3, 20246 citations

Generating and verifying entanglement of itinerant microwave modes

Hsiang‐Sheng Ku, William Kindel, Scott Glancy +5 more

Bulletin of the American Physical SocietyMar 19, 20130 citations

Theory of a two-mode entanglement amplifier

Yunxia Ping, Bo Zhang, Ze Cheng

Physics Letters AMar 15, 20075 citations

Perspectives of microwave quantum key distribution in the open air

Florian Fesquet, Fabian Kronowetter, Michael Renger +8 more

One of the cornerstones of quantum communication is the unconditionally secure distribution of classical keys between remote parties. This key feature of quantum technology is based on the quantum properties of propagating electromagnetic waves, such as entanglement, or the no-cloning theorem. However, these quantum resources are known to be susceptible to noise and losses, which are omnipresent in open-air communication scenarios. In this paper, we theoretically investigate the perspectives of continuous-variable open-air quantum key distribution at microwave frequencies. In particular, we present a model describing the coupling of propagating microwaves with a noisy environment. Using a protocol based on displaced squeezed states, we demonstrate that continuous-variable quantum key distribution with propagating microwaves can be unconditionally secure with communication at room temperature up to distances of around 200 m, limited by the total coupled noise photon number. Moreover, we show that microwaves can potentially outperform conventional quantum key distribution at telecom wavelengths and imperfect weather conditions.One of the cornerstones of quantum communication is the unconditionally secure distribution of classical keys between remote parties. This key feature of quantum technology is based on the quantum properties of propagating electromagnetic waves, such as entanglement, or the no-cloning theorem. However, these quantum resources are known to be susceptible to noise and losses, which are omnipresent in open-air communication scenarios. In this paper, we theoretically investigate the perspectives of continuous-variable open-air quantum key distribution at microwave frequencies. In particular, we present a model describing the coupling of propagating microwaves with a noisy environment. Using a protocol based on displaced squeezed states, we demonstrate that continuous-variable quantum key distribution with propagating microwaves can be unconditionally secure with communication at room temperature up to distances of around 200 m, limited by the total coupled noise photon number. Moreover, we show that microwaves can potentially outperform conventional quantum key distribution at telecom wavelengths and imperfect weather conditions.

arXiv:2203.05530Physical Review ASep 14, 202321 citations

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