This talk will provide a brief overview and introduction to superconducting qubits: their historical development, their current use, and future prospects.

Quantum noise plays an important role in limiting the sensitivity of current interferometric gravitational (GW) wave detectors. For this reason, in recent years all international collaborations have undertaken an R&D campaign aimed at overcoming the Standard Quantum Limit for GW detectors. The strategy employed is based on the use of squeezed vacuum states injected in to the detector port of...

The axion is a hypothetical particle that may solve two problems in particle physics & cosmology, the Strong-CP problem and the nature of dark matter. The Axion Dark Matter Experiment (ADMX), which started at LLNL in the mid-1990s, is the DOE Flagship search for these particles. The experiment uses tunable resonant cavities in a large static magnetic field to enhance the conversion of axions...

Haloscopes consisting of a microwave cavity with a high quality factor (Q) connected to low-noise electronics have been deployed to detect wavelike axions and dark photons. But the dark matter mass is unknown, so haloscopes must be tunable to search through the photon coupling vs. mass parameter space. Therefore, the scan rate for haloscope experiments is a crucial figure of merit and is...

At ultra-low temperatures (ULT) macroscopic quantum states form, such as superfluids, that have unique potential as quantum sensors for rare interactions. The QUEST-DMC QTFP project is deploying this technology at two sites capable of reaching ULT, Royal Holloway (RHUL) and Lancaster University (ULANC), both members of the European Microkelvin Platform, EMP (https://emplatform.eu/). QUEST-DMC...

Axion Dark Matter, Dark Photon Dark matter and Millicharged particle dark matter are some of the simplest and popular models of dark matter and are looked for in various experiments. Yet, there continue to exist inaccessible regions in interaction and mass parameter space for these models. In this talk I propose a new way to detect the tiny electric fields produced by these dark matter...

Quantum sensors offer the most promising way to detect a number of light, weakly coupled particles, such as gravitons or axions. Cavities, as well as other optomechanical systems, are current realizations of such sensors in operation. I will discuss how a theoretical tool from quantum optics, the input-output formalism, allows calculation and understanding of the sensitivity of these...

Until fault-tolerance becomes implementable at scale, quantum computing will heavily rely on noise mitigation techniques. Entering the era of quantum utility and performing complex enough quantum simulation requires the use of efficient and scalable noise mitigation strategies.

While methods such as zero noise extrapolation with probabilistic error amplification (ZNE-PEA) and probabilistic...

I will report about a haloscope experiment in which a hybrid surfaced (copper-NbTi) cavity immersed in a 2 T-magnetic field has been readout by a transmon-based single microwave photon detector (SMPD). The cavity frequency could be varied to probe for different axion masses around 30.5 microelectronvolt by means of a nanopositioner, and I will report about the upper limit that we obtained on...

We introduce the Broadband Reflector Experiment for Axion Detection (BREAD) conceptual design and science program. BREAD is a dish antenna experiment based on a coaxial cylindrical reflector design which converts axions or dark photons into ordinary photons and focuses them onto a small sensor. This unique geometry is well matched to the requirements of superconducting quantum sensors since...

We prepare to set up a new project to detect high frequency GW, starting with the existing cavity from the MAGO collaboration, which will be used for R&D studies and for a first measurement together with Fermilab. We will present the status of the first inspection of the cavity fabricated about 15years ago. In addition, we will show our current results of our theoretical analysis of the...

At Fermilab we are working with DESY and INFN to revive the MAGO experiment. We started several activities in preparation for the arrival of the cavity onsite in order to be able to successfully cold test the cavity and successively conduct a GW search.

There are several proposed experiments to search for Dark Matter that will utilize SRF cavities submerged into liquid Helium. Extremely...

I will summarize recent proposals of applying quantum sensing technology, such as squeezing, entanglement and transduction to dark matter search. The sensing platform includes microwave cavities and optomechanical sensors.

Lithium niobate is a leading material for integrated optics for quantum and classical applications. Because of its nonlinearity, it supports the fabrication of electro-optical devices for quantum state generation and manipulation. Using this material platform, I will show our experimental results on the generation of squeezed vacuum state on chip, frequency conversion of single photons, and...

The Laboratori Nazionali del Gran Sasso (LNGS) is a deep-underground research facility located in Italy. The facility is surrounded by 1.4 kilometers of rock, which acts as a natural shield against cosmic rays. In this talk, I will present the "Round Robin" project, in which we aim to circulate the same qubit prototype in multiple SQMS testbeds to disentangle the sources of decoherence. I will...

Kaplan and Rajendran have recently demonstrated that non-linear and state-dependent terms can be consistently added to quantum field theory to yield causal non-linear time evolution in quantum mechanics. Causal non-linear theories have the unavoidable feature that their quantum effects are dramatically sensitive to the full physical spread of the quantum state of the system. As a result, such...

Long-baseline light-pulse atom interferometry (LPAI) is a powerful tool for performing tests of fundamental physics (see [1] and reference therein). Using state-of-the-art technology for coherent manipulation of ultracold (picoKelvin) atoms, LPAI is capable of creating quantum superpositions over tens of meters. Moreover, due to acceleration sensitivities close to 10-14 m/s2, using (say) a 100...

We provide the optimal measurement strategy for a class of noisy channels that reduce to the identity channel for a specific value of a parameter (spreading channels). We provide an example that is physically relevant: the estimation of the absolute value of the displacement in the presence of phase randomizing noise. This channel is useful to model axion dark matter search.

Surprisingly,...

We start from a description of the current challenges in quantum computing for simulation and quantum hardware control in view of applications in HEP. We discuss the role of middleware development for quantum computing. We describe recent applications of quantum computing to high-energy physics for parton distribution functions determinations and Monte Carlo simulation. We conclude by...

We present quasiprobability methods that are aimed at effectively reducing or tailoring the quantum noise present in the output of noisy hardware simulations. These methods rely on a tomographic characterization of noisy quantum channels and then proceed by decomposing the desired quantum channels in terms of the noisy implementable ones. We discuss applications of these techniques to quantum...

There are many directions to explore in fundamental physics. I will tell why quantum gravity is the most promising and urgent, and will point to specific theoretical open issues, related to black hole entropy, that need to be settled with an experiment. This can eventually open the doors to the next era.

Then I will discuss why this program can be pursued by using equivalences between...

In the past few years we have witnessed a growing interest computational paradigms beyond the gate paradigm. Among these Extreme learning machines and Reservoir computers are two particularly interesting new computational paradigms. They key feature is the use of a fixed, nonlinear dynamics to efficiently extract information from a given dataset. Such goal, in the classical scenario, is...

The development of optical quantum technologies allows for quantum-enhanced metrology, secure quantum communication, and quantum computing and simulation in highly increased dimensions. Maturing quantum photonics requires efficient generation and detection of single photons, as well as their scalable manipulation. We merge highly efficient multi-photon sources and integrated waveguide...

In this talk I will outline a novel approach to quantum mereology based on minimal information scrambling. Generalized quantum subsystems are defined by pairs of von Neumann algebras and their scrambling in terms of an Algebraic Out of Time Order Correlation (A-OTOC) function. The short time expansion of the A-OTOC allows one to define a notion of Gaussian Scrambling rate. The latter has a...

Several quantities of interest in physics are non-linear functions of the density matrix and cannot, even in principle, correspond to proper quantum observables. Any method aimed to determine the value of these quantities should resort to indirect measurements and thus corresponds to a parameter estimation problem whose solution, i.e. the determination of the most precise estimator,...