Lifeboat Foundation

Quantum-enhanced single-parameter estimation is an established capability, with non-classical probe states achieving precisions beyond what can be reached by the equivalent classical resources in photonic^1,2,3, trapped-ion^4,5, superconducting⁶ and atomic^7,8 systems. This has paved the way for quantum enhancements in practical sensing applications, from gravitational wave detection⁹ to biological imaging¹⁰. For single-parameter estimation, entangled probe states are sufficient to reach the ultimate allowed precisions. However, for multi-parameter estimation, owing to the possible incompatibility of different observables, entangling resources are also required at the measurement stage. The ultimate attainable limits in quantum multi-parameter estimation are set by the Holevo Cramér–Rao bound (Holevo bound)^11,12. In most practical scenarios, it is not feasible to reach the Holevo bound as this requires a collective measurement on infinitely many copies of the quantum state^13,14,15,16 (see Methods for a rigorous definition of collective measurements). Nevertheless, it is important to develop techniques that will enable the Holevo bound to be approached, given that multi-parameter estimation is fundamentally connected to the uncertainty principle¹⁷ and has many physically motivated applications, including simultaneously estimating phase and phase diffusion^18,19, quantum super-resolution^20,21, estimating the components of a three-dimensional field^22,23 and tracking chemical processes²⁴. Furthermore, as we demonstrate, collective measurements offer an avenue to quantum-enhanced sensing even in the presence of large amounts of decoherence, unlike the use of entangled probe states^25,26.

To date, collective measurements for quantum multi-parameter metrology have been demonstrated exclusively on optical systems^{27,28,29,30,31,32}. Contemporary approaches to collective measurements on optical systems are limited in their scalability: that is, it is difficult to generalize present approaches to measuring many copies of a quantum state simultaneously. The limited gate set available can also make it harder to implement an arbitrary optimal measurement. Indeed, the collective measurements demonstrated so far have all been restricted to measuring two copies of the quantum state and, while quantum enhancement has been observed, have all failed to reach the ultimate theoretical limits on separable measurements^33,34. Thus, there is a pressing need for a more versatile and scalable approach to implementing collective measurements.

In this work, we design and implement theoretically optimal collective measurement circuits on superconducting and trapped-ion platforms. The ease with which these devices can be reprogrammed, the universal gate set available and the number of modes across which entanglement can be generated, ensure that they avoid many of the issues that current optical systems suffer from. Using recently developed error mitigation techniques³⁵ we estimate qubit rotations about the axes of the Bloch sphere with a greater precision than what is allowed by separable measurements on individual qubits. This approach allows us to investigate several interesting physical phenomena: we demonstrate both optimal single-and two-copy collective measurements reaching the theoretical limits^33,34. We also implement a three-copy collective measurement as a first step towards surpassing two-copy measurements. However, due to the circuit complexity, this measurement performs worse than single-copy measurements. We investigate the connection between collective measurements and the uncertainty principle. Using two-copy collective measurements, we experimentally violate a metrological bound based on known, but restrictive uncertainty relations³⁶. Finally, we compare the metrological performance of quantum processors from different platforms, providing an indication of how future quantum metrology networks may look.

The ultraviolet nail polish drying devices used to cure gel manicures may pose more of a public health concern than previously thought. Researchers at the University of California San Diego studied these ultraviolet (UV) light emitting devices, and found that their use leads to cell death and cancer-causing mutations in human cells.

The devices are a common fixture in nail salons, and generally use a particular spectrum of UV light (340-395nm) to cure the chemicals used in gel manicures. While tanning beds use a different spectrum of UV light (280-400nm) that studies have conclusively proven to be carcinogenic, the spectrum used in the nail dryers has not been well studied.

“If you look at the way these devices are presented, they are marketed as safe, with nothing to be concerned about,” said Ludmil Alexandrov, a professor of bioengineering as well as cellular and molecular medicine at UC San Diego, and corresponding author of the study published Jan. 17 in Nature Communications. “But to the best of our knowledge, no one has actually studied these devices and how they affect human cells at the molecular and cellular levels until now.”

Lasers are intense beams of colored light. Depending on their color and other properties, they can scan your groceries, cut through metal, eradicate tumors, and even trigger nuclear fusion. But not every laser color is available with the right properties for a specific job.

To fix that, scientists have found a variety of ways to convert one color of laser light into another. In a study just published in the journal Physical Review Applied, scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory demonstrate a new color-shifting strategy that is simple, efficient, and highly customizable.

The new method relies on interactions between the laser and vibrational energy in the chemical bonds of materials called “ionic liquids.” These liquids are made only of positively and negatively charged ions, like ordinary table salt, but they flow like viscous fluids at room temperature. Simply shining a laser through a tube filled with a particular ionic liquid can downshift the laser’s energy and change its color while retaining other important properties of the laser beam.

University of California, Berkeley, chemists have created a new type of material from millions of identical, interlocking molecules, that for the first time allows the synthesis of extensive 2D or 3D structures that are flexible, strong and resilient, like the chain mail that protected medieval knights.

The material, called an infinite catenane, can be synthesized in a single chemical step.

Continue reading “New ‘chain mail’ material of interlocking molecules is tough, flexible and easy to make” »

In a recent article published in Nature Materials, researchers reported a conductance-based organic electrochemical neuron (c-OECN) that mimicked biological signaling in neurons, especially activation/inactivation of their sodium and potassium channels.

Compilation of the top interviews, articles, and news in the last year.

Scientists at University of Galway delved into the issue of antimicrobial resistance—one of the greatest threats to human health—discovering the potential to improve treatment options for superbug MRSA infections using penicillin-type antibiotics that have become ineffective on their own.

The research has been published in the journal mBio.

Professor James P O’Gara and Dr. Merve S Zeden in the School of Biological and Chemical Sciences, University of Galway, led the study.

Atomic force microscopy (AFM) is a popular technique for interrogating surfaces on the micro and nano scales. The most common use for AFM is imaging; however, there are a variety of more specialized AFM techniques that can be used to determine electrical, mechanical, and chemical properties of surfaces. To adequately control the application of forces to surfaces for these techniques (especially mechanical property measurements), accurate stiffness calibrations of test cantilevers should be used.

There are a variety of test cantilever stiffness calibration techniques available, based on dimensional, static force and displacement, and dynamic vibrational methods, but in general, these have large uncertainties in the range of ± 10% to ± 30% and unknown accuracy. More rigorous calibrated balance techniques, with SI traceability have been pioneered, mostly by National Metrology Institutes (NMIs), but their complexity, expense, and time-consuming operation make them an out-of-reach technique for most AFM researchers. The reference cantilevers represented by NIST SRM 3,461 are an accurate and precise force calibration artifact for use in the field.

SRM 3,461 is a silicon microfabricated device containing seven cantilevers of carrying length and stiffness is used for validating methods for determining the stiffness of atomic force microscope (AFM) cantilevers as well as directly calibrating AFM test cantilevers using the reference cantilever method.

Scientists have developed a wireless, battery-free implant capable of monitoring dopamine signals in the brain in real-time in small animal models, an advance that could aid in understanding the role neurochemicals play in neurological disorders.

The device, detailed in a study published in ACS Nano, activates or inhibits specific neurons in the brain using light, a technique known as optogenetic stimulation. It also records dopamine activity in freely behaving subjects without the need for bulky or prohibitive sensing equipment, said John Rogers, Ph.D., the Louis Simpson and Kimberly Querrey Professor of Materials Science and Engineering, Biomedical Engineering and Neurological Surgery, and a co-author of the study.

“This device allows neuroscientists to monitor and modulate brain activity in real-time and in a programmable fashion, in mice—a very important class of animal model for neuroscience studies,” Rogers said.

There are many ways to initiate chemical reactions in liquids, but placing free electrons directly into water, ammonia and other liquid solutions is especially attractive for green chemistry because solvated electrons are inherently clean, leaving behind no side products after they react.

In theory, solvated electrons could be used to safely and sustainably break down carbon dioxide or chemical pollutants in contaminated water, but it has been impractical to find out because they’ve been difficult and expensive to make in pure form.

That could change thanks to new research from chemists at Rice University, Stanford University and the University of Texas at Austin. In a published study in the Proceedings of the National Academy of Sciences, researchers from the Center for Adapting Flaws into Features (CAFF) uncovered the long-sought mechanism of a well-known but poorly understood process that produces solvated electrons via interactions between light and metal.