--> Quantum Physics arXiv:2603.05583 (quant-ph) [Submitted on 5 Mar 2026] Title:In-situ Characterization of Light-Matter Coupling in Multimode Circuit-QED Systems Authors:Kellen O'Brien, Won Chan Lee, Alexandra Behne, Ali Fahimniya, Yu-Xin Wang, Maya Amouzegar, Alexey V. Gorshkov, Alicia J. Kollár View a PDF of the paper titled In-situ Characterization of Light-Matter Coupling in Multimode Circuit-QED Systems, by Kellen O'Brien and 7 other authors View PDF HTML (experimental) Abstract:Multimode cavity-QED systems can be leveraged to explore a wide range of physical phenomena; however, a complex multimode environment makes systematic characterization of light-matter interactions challenging. Here we present a general measurement protocol, applicable to both atomic and synthetic cavity-QED systems, that enables the determination of coupling to individual photonic modes. The method leverages measurements of the AC-Stark and Kerr effects, along with known detuning dependencies, to eliminate the need for single-photon resolution, independent photon-number calibration, or insertion-loss calibration. We demonstrate the method using a superconducting transmon qubit coupled to a one-dimensional microwave resonator lattice. We validate the consistency of the extracted light-matter couplings $g$ determined at multiple qubit detunings, and from the self-Kerr and cross-Kerr shifts for three photon modes, which provide separate measurements of $g$ for each of the three modes. Subjects: Quantum Physics (quant-ph); Atomic Physics (physics.atom-ph) Cite as: arXiv:2603.05583 [quant-ph] &nbsp; (or arXiv:2603.05583v1 [quant-ph] for this version) &nbsp; https://doi.org/10.48550/arXiv.2603.05583 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Kellen O'Brien [view email] [v1] Thu, 5 Mar 2026 19:00:00 UTC (2,450 KB) Full-text links: Access Paper: View a PDF of the paper titled In-situ Characterization of Light-Matter Coupling in Multimode C

Google

NASA

superconducting qubits

arXiv Quantum Physics

In-situ Characterization of Light-Matter Coupling in Multimode Circuit-QED Systems

in-situ-characterization-light-matter-coupling-multimode-circuit-qed-systems

--> Quantum Physics arXiv:2603.05595 (quant-ph) [Submitted on 5 Mar 2026] Title:Two-dimensional matter-wave interferometer, rotational dynamics, and spin contrast Authors:Ryan Rizaldy, Shrestha Mishra, Anupam Mazumdar View a PDF of the paper titled Two-dimensional matter-wave interferometer, rotational dynamics, and spin contrast, by Ryan Rizaldy and 2 other authors View PDF HTML (experimental) Abstract:We investigate a two-dimensional matter-wave interferometer where both spatial and rotational dynamics of a nanoparticle are intertwined in closing the one-loop interferometer in the Stern-Gerlach type setup. We consider the spin-contrast of the nitrogen-vacancy (NV) centred nanodiamond in combination with a two-dimensional magnetic field setup to extend the one-dimensional Stern--Gerlach interferometry. We analyse the dynamical motion along with the rigid rotation under the influence of the external magnetic field. Regarding rotation, we incorporate Euler-angle dynamics to analyse the stability of rotational degrees of freedom and their influence on the spin contrast to address the Humpty-Dumpty problem. We show that by imparting external rotation provides the gyroscopic stability to the liberating mode of the NV-spin and hence helps to improve the contrast. Our scheme creates a tiny spatial superposition of size $\sim 0.21~{\rm \mu m}$ for mass $m=10^{-17}$kg in less than $t\sim 0.013$s. Comments: Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2603.05595 [quant-ph] &nbsp; (or arXiv:2603.05595v1 [quant-ph] for this version) &nbsp; https://doi.org/10.48550/arXiv.2603.05595 Focus to learn more arXiv-issued DOI via DataCite Submission history From: Ryan Rizaldy [view email] [v1] Thu, 5 Mar 2026 19:00:10 UTC (1,541 KB) Full-text links: Access Paper: View a PDF of the paper titled Two-dimensional matter-wave interferometer, rotational dynamics, and spin contrast, by Ryan Rizaldy and 2 other authorsView PDFHTML (experimental)TeX Source view license Current browse con

Two-dimensional matter-wave interferometer, rotational dynamics, and spin contrast

two-dimensional-matter-wave-interferometer-rotational-dynamics-spin-contrast

The Trade Desk (TTD 1.75%) enters 2026 in a very different position than it was in just a few years ago. For most of the past decade, the company enjoyed near-flawless execution. Revenue beat expectations quarter after quarter, and customer retention remained consistently above 90%. Unsurprisingly, investors rewarded that consistency with a premium valuation. But 2025 changed the tone. Competition intensified. Execution wobbled. And the advertising landscape shifted more decisively toward large ecosystems with powerful first-party data. The Trade Desk remains a strong business. But the real question now is whether it can prove its structural advantage in a tougher environment. Here are three things The Trade Desk must prove in 2026. Image source: Getty Images. Kokai must deliver durable, measurable performance gains Launched as the latest artificial intelligence (AI)-enabled platform, Kokai is no longer a product rollout story. It's now the foundation of the company's future. Management stated that nearly all clients run campaigns through Kokai. That milestone shifts the conversation from adoption to outcomes. In 2026, investors won't care about how many advertisers use Kokai. They will care about whether it consistently drives superior results. The company has highlighted meaningful improvements in cost per acquisition, reach efficiency, and engagement metrics. If those gains persist across verticals and economic cycles, Kokai becomes a durable competitive advantage. But here's the challenge: Amazon, Google, and Meta are also embedding AI deeply into their advertising stacks. Every major platform now claims smarter optimization. The Trade Desk must prove that its AI performs better in an open, multi-publisher environment than in walled gardens. That means demonstrating: Sustained lower cost per action (CPA) relative to peers. Higher return on ad spend across industries. Increased advertiser spend driven by measurable lift. If Kokai drives consistent performance imp

Amazon

Intel

Advantage

The Motley Fool

3 Things The Trade Desk Must Prove in 2026

things-trade-desk-must-prove-2026

Researchers at the University of Twente are addressing a critical challenge in quantum computing by significantly reducing the number of photons required to create a reliable qubit. Frank Somhorst, a PhD candidate at the university, has developed a method for photonic quantum computers that combines multiple imperfect photons into a single, higher-quality photon, potentially decreasing the required photon count per logical qubit by a factor of four. “That feels like waste,” says Somhorst, referring to the current need for hundreds of components per qubit; “You build a machine, but under the hood you’re throwing away huge amounts of light to correct mistakes.” This innovation, tested with QuiX Quantum on integrated hardware and subject to a patent application, promises to simplify construction, reduce error correction demands, and accelerate the path toward scalable quantum systems. Photonic Qubit Optimization via Imperfect Photon Consolidation This innovation addresses a fundamental challenge: while photons offer stability and speed ideal for quantum computing, their inherent imperfections necessitate extensive error correction, adding significant complexity and cost. “That feels like waste,” says Somhorst, explaining the impetus behind his research. Somhorst’s technique centers on an optical circuit designed to improve photons, effectively selecting the best characteristics from a group of imperfect ones before they are used in calculations. Rather than constantly correcting errors arising from slight variations in photon arrival times or frequencies, this method proactively improves the quality of the input light. “Instead of continually correcting errors after the fact, we first improve the quality of the light itself,” he explains, highlighting the logical efficiency of the approach. Initial models suggest a conservative fourfold reduction in the number of photons required per logical qubit, a substantial improvement in resource utilization. The research has mov

Xanadu

photonic qubits

Quantum Zeitgeist

University of Twente Researchers Reduce Photonic Qubit Costs with Photon Filtering

university-twente-researchers-reduce-photonic-qubit-costs-photon

Welcome to this week’s Quantum Technology Digest! We’ve curated the ten most impactful stories shaping the rapidly evolving landscape of quantum computing and related fields. This week highlights a fascinating mix of progress – from hardware advancements and significant funding rounds to demonstrable scientific breakthroughs utilizing quantum power. Notably, this week’s news showcases a strong push toward scalability and error correction, crucial hurdles in realizing practical quantum computers. Several articles detail advancements in qubit technology – including Rigetti’s CZ gate implementation, Xanadu’s modular Aurora platform, and Quantum Elements’ record-breaking fidelity in logical qubits – alongside robust investment in neutral atom approaches from Pasqal and recognized leadership from Harvard/CNRS/Paris-Saclay/Wisconsin-Madison. Beyond the hardware, we see quantum computing tackling complex scientific challenges, as demonstrated by IBM’s molecular validation. Finally, the global race for quantum dominance continues to heat up, with both China and Canada outlining ambitious plans and significant investment in the sector. This week’s digest underscores the breadth of innovation happening now, spanning multiple platforms, geographical locations, and application areas – a clear sign the quantum revolution is gaining momentum. 1. Rigetti Computing: 2025 Progress, Losses, and Key Partnerships Quantum Zeitgeist Weekly Digest Rigetti Computing announced its 2025 financial results, reporting $7.1 million in revenue alongside a $216.2 million net loss, reflecting the high costs of quantum hardware development. However, the company showcased significant technical achievements, notably achieving 99.9% two-qubit gate fidelity with a 28 nanosecond gate speed on a prototype platform and demonstrating consistent high one-qubit gate fidelity. This progress is bolstered by an $8.4 million order from India’s C-DAC for a 108-qubit on-premises quantum computer, signaling growing 

Rigetti

Pasqal

QuEra

Harvard

Oxford

DARPA

neutral atoms

PennyLane

108-qubit system

127-qubit system

by an $8.4 million order from India’s C-DAC for a...

of 91-94% for entangled logical qubits on an IBM 127-qubit...

. Achieving speeds under 30 nanoseconds with over 99.9% fidelity,...

Quantum Zeitgeist Weekly Digest

quantum-zeitgeist-weekly-digest

Leo Nelissen50.2K FollowersFollow5ShareSavePlay(14min)Comments(2)SummaryVista Energy, S.A.B. de C.V., is a Strong Buy, benefiting from rapid production growth, high ROACE, and robust free cash flow in Argentina's Vaca Muerta shale.VIST projects $1.5B cumulative FCF (2026–2028) at $65 Brent, implying a 9% yield, rising to 14% at $75 Brent, with significant shareholder returns.Builders FirstSource, Inc., is also rated Strong Buy, leveraging M&amp;A, value-added products, and tech adoption to capitalize on a bottoming housing market.BLDR trades at 14.2x earnings, below historical averages, with a path to &gt;$200/share in 2–3 years as housing recovers and margins expand.Introduction Have you ever heard of the “hyper-financialization” of everyday life? That’s basically the description of a world where we can literally bet on anything, whenever we want. I’m talking about prediction markets, which were just covered by The WallThis article was written byLeo Nelissen50.2K FollowersFollowLeo Nelissen is a long-term investor and macro-focused strategist with a passion for dividend growth, high-quality compounders, and structural investment themes. He combines big-picture macro analysis with bottom-up stock research to identify durable businesses with strong cash-flow potential. Leo also writes for Main Street Alpha, where he publishes deeper-dive research and actionable investment ideas for long-term investors.Analyst’s Disclosure: I/we have a beneficial long position in the shares of QXO either through stock ownership, options, or other derivatives. I wrote this article myself, and it expresses my own opinions. I am not receiving compensation for it (other than from Seeking Alpha). I have no business relationship with any company whose stock is mentioned in this article. Seeking Alpha's Disclosure: Past performance is no guarantee of future results. No recommendation or advice is being given as to whether any investment is suitable for a particular investor. Any views or opi

The Future of Quantum Computing

In-situ Characterization of Light-Matter Coupling in Multimode Circuit-QED Systems

Latest News

Two-dimensional matter-wave interferometer, rotational dynamics, and spin contrast

3 Things The Trade Desk Must Prove in 2026

University of Twente Researchers Reduce Photonic Qubit Costs with Photon Filtering

Latest News

In-situ Characterization of Light-Matter Coupling in Multimode Circuit-QED Systems

Two-dimensional matter-wave interferometer, rotational dynamics, and spin contrast

3 Things The Trade Desk Must Prove in 2026

University of Twente Researchers Reduce Photonic Qubit Costs with Photon Filtering

Quantum Zeitgeist Weekly Digest

For The First Time, I'm Covering These 2 Stocks - And I See Huge Upside

Trending Stories

Get the Quantum News Newsletter

India National Quantum Mission