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1. Temporally Localized Quantum Operations on Continuous-Wave Thermal Light

   https://doi.org/10.1103/y4v8-1wgm  

   Wang, Yunkai; Zhang, Yujie; Lorenz, Virginia O (September 2025, Physical Review Letters)

   Previous work showed that thermal light with a blackbody spectrum cannot be decomposed into a mixture of independent localized pulses. However, we find that in the weak-source limit and under the assumption of a flat spectrum, the first nonvacuum term in the state expansion does form a mixture of such pulses. This decomposition is essential for quantum-enhanced astronomical interferometry, which typically operates on localized pulses even though stellar light is inherently continuous-wave. We present a quantum derivation of the van Cittert–Zernike theorem that incorporates finite bandwidth, thereby justifying the operations on localized pulses while processing continuous-wave thermal light. For general spectra in the weak-source limit, we establish a criterion under which correlations between pulses can be safely neglected. When this criterion is not met, we provide a corrected strategy that accurately accounts for both the spectral profile and the detector-defined pulse shape. 

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2. Circumvent traffic shaping using virtual wireless clients in IEEE 802.11 wireless local area network

   https://doi.org/10.1109/MILCOM.2017.8170854  

   Nakhila, Omar; Zou, Cliff (October 2017, MILCOM 2017 - 2017 IEEE Military Communications Conference (MILCOM))

   Accessing the Internet through Wi-Fi networks offers an inexpensive alternative for offloading data from mobile broadband connections. Businesses such as fast food restaurants, coffee shops, hotels, and airports, provide complimentary Internet access to their customers through Wi-Fi networks. Clients can connect to the Wi-Fi hotspot using different wireless devices. However, network administrators may apply traffic shaping to control the wireless client's upload and download data rates. Such limitation is used to avoid overloading the hotspot, thus providing fair bandwidth allocation. Also, it allows for the collection of money from the client in order to have access to a faster Internet service. In this paper, we present a new technique to avoid bandwidth limitation imposed by Wi-Fi hotspots. The proposed method creates multiple virtual wireless clients using only one physical wireless interface card. Each virtual wireless client emulates a standalone wireless device. The combination of the individual bandwidth of each virtual wireless client results in an increase of the total bandwidth gained by the attacker. Our proposed technique was implemented and evaluated in a real-life environment with an increase in data rate up to 16 folds. 

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3. Tunable FSRS measurements with reduced background signals: Using an etalon filter to generate picosecond pump pulses in the 460–650 nm range

   https://doi.org/10.1063/5.0237444  

   Lorenzo, Emmaline R; Karki, Birendra; White, Katie E; Burns, Kristen H; Elles, Christopher G (December 2024, The Journal of Chemical Physics)

   Generating wavelength-tunable picosecond laser pulses from an ultrafast laser source is essential for femtosecond stimulated Raman scattering (FSRS) measurements. Etalon filters produce narrowband (picosecond) pulses with an asymmetric temporal profile that is ideal for stimulated resonance Raman excitation. However, direct spectral filtering of femtosecond laser pulses is typically limited to the laser’s fundamental and harmonic frequencies due to very low transmission of broad bandwidth pulses through an etalon. Here, we show that a single etalon filter (15 cm−1 bandwidth; 172 cm−1 free spectral range) provides an efficient and tunable option for generating Raman pump pulses over a wide range of wavelengths when used in combination with an optical parametric amplifier and a second harmonic generation (SHG) crystal that has an appropriate phase-matching bandwidth for partial spectral compression before the etalon. Tuning the SHG wavelength to match individual transmission lines of the etalon filter gives asymmetric picosecond pump pulses over a range of 460–650 nm. Importantly, the SHG crystal length determines the temporal rise time of the filtered pulse, which is an important property for reducing background and increasing Raman signals compared with symmetric pulses having the same total energy. We examine the wavelength-dependent trade-off between spectral narrowing via SHG and the asymmetric pulse shape after transmission through the etalon. This approach provides a relatively simple and efficient method to generate tunable pump pulses with the optimum temporal profile for resonance-enhanced FSRS measurements across the visible region of the spectrum. 

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4. On the Energy-Delay Tradeoff in Streaming Data: Finite Blocklength Analysis

   Baig, Mirza; Yu, Lei; Xiong, Zixiang; Høst-Madsen, Anders; Li, Houqiang; and Li, Weiping (December 2019, IEEE transactions on information theory)

   This paper investigates basic trade-offs between energy and delay in wireless communication systems using finite blocklength theory. We first assume that data arrive in constant stream of bits, which are put into packets and transmitted over a communications link. Our results show that depending on exactly how energy is measured, in general energy depends on sqrt{d^{-1}} or sqrt{d^{-1}log d}, where d is the delay. This means that the energy decreases quite slowly with increasing delay. Furthermore, to approach the absolute minimum of -1.59 dB on energy, bandwidth has to increase very rapidly, much more than what is predicted by infinite blocklength theory. We then consider the scenario when data arrive stochastically in packets and can be queued. We devise a scheduling algorithm based on finite blocklength theory and develop bounds for the energy-delay performance. Our results again show that the energy decreases quite slowly with increasing delay. 

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5. NetScatter: Enabling Large-Scale Backscatter Networks

   Hessar, Mehrdad; Najafi, Ali; Gollakota, Shyamnath (February 2019, NSDI)

   We present the first wireless protocol that scales to hundreds of concurrent transmissions from backscatter devices. Our key innovation is a distributed coding mechanism that works below the noise floor, operates on backscatter devices and can decode all the concurrent transmissions at the receiver using a single FFT operation.Our design addresses practical issues such as timing and frequency synchronization as well as the near-far problem. We deploy our design using a testbed of backscatter hardware and show that our protocol scales to concurrent transmissions from 256 devices using a bandwidth of only 500 kHz.Our results show throughput and latency improvements of14–62x and 15–67x over existing approaches and 1–2 orders of magnitude higher transmission concurrency. 

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