For the first time, astronomers located a molecular cloud by detecting hydrogen, its key component, rather than other molecules like carbon monoxide that not all such clouds contain.
Satellite operator Spire Global has closed the $241 million sale of its commercial maritime tracking business to Belgian analytics provider Kpler, ending a legal dispute over the stalled transaction.
A massive blackout affecting Spain, Portugal, and parts of France has been blamed on atmospheric conditions. Now engineers face the arduous task of getting the power back on.
India must intensify its efforts in quantum technologies as well as boost private investment if it is to become a leader in the burgeoning field. That is according to the first report from Indiaâs National Quantum Mission (NQM), which also warns that the country must improve its quantum security and regulation to make its digital infrastructure quantum-safe.
Approved by the Indian government in 2023, the NQM is an eight-year $750m (60bn INR) initiative that aims to make the country a leader in quantum tech. Its new report focuses on developments in four aspects of NQMâs mission: quantum computing; communication; sensing and metrology; and materials and devices.
Entitled Indiaâs International Technology Engagement Strategy for Quantum Science, Technology and Innovation, the report finds that Indiaâs research interests include error-correction algorithms for quantum computers. It is also involved in building quantum hardware with superconducting circuits, trapped atoms/ions and engineered quantum dots.
The NQM-supported Bengaluru-based startup QPiAI, for example, recently developed a 25-superconducting qubit quantum computer called âIndusâ, although the qubits were fabricated abroad.
Ajay Sood, principal scientific advisor to the Indian government, told Physics World that while India is strong in âsoftware-centric, theoretical and algorithmic aspects of quantum computing, work on completely indigenous development of quantum computing hardware isâŚat a nascent stage.â
Sood, who is a physicist by training, adds that while there are a few groups working on different platforms, these are at less than 10-qubit stage. â[It is] important for [India] to have indigenous capabilities for fabricating qubits and other ancillary hardware for quantum computers,â he says
India is also developing secure protocols and satellite-based systems and implementing quantum systems for precision measurements. QNu Labs â another Begalaru startup â is, for example, developing a quantum-safe communication-chip module to secure satellite and drone communications with built-in quantum randomness and security micro-stack.
Lagging behind
The report highlights the need for greater involvement of Indian industry in hardware-related activities. Unlike other countries, India struggles with limited industry funding, in which most comes from angel investors, with limited participation from institutional investors such as venture-capital firms, tech corporates and private equity funds.
There are many areas of quantum tech that are simply not being pursued in India
Arindam Ghosh
The report also calls for more indigenous development of essential sensors and devices such as single-photon detectors, quantum repeaters, and associated electronics, with necessary testing facilities for quantum communication. âThere is also room for becoming global manufacturers and suppliers for associated electronic or cryogenic components,â says Sood. âOur industry should take this opportunity.â
India must work on its quantum security and regulation as well, according to the report. It warns that the Indian financial sector, which is one the major drivers for quantum tech applications, ârisks lagging behindâ in quantum security and regulation, with limited participation of Indian financial-service providers.
âOur cyber infrastructure, especially related to our financial systems, power grids, and transport systems, need to be urgently protected by employing the existing and evolving post quantum cryptography algorithms and quantum key distribution technologies,â says Sood.
India currently has about 50 educational programmes in various universities and institutions. Yet Arindam Ghosh, who runs the Quantum Technology Initiative at the India Institute of Science, Bangalore, says that the country faces a lack of people going into quantum-related careers.
âIn spite of [a] very large number of quantum-educated graduates, the human resource involved in developing quantum technologies is abysmally small,â says Ghosh. âAs a result, there are many areas of quantum tech that are simply not being pursued in India.â Other problems, according to Ghosh, include âmodestâ government funding compared to other countries as well as âslow and highly bureaucraticâ government machinery.
Sood, however, is optimistic, pointing out recent Indian initiatives such as setting up hardware fabrication and testing facilities, supporting start-ups as well as setting up a $1.2bn (100bn INR) fund to promote âdeep-techâ startups. â[With such initiatives] there is every reason to believe that India would emerge even stronger in the field,â says Sood.
A new theoretical framework proposes that gravity may arise from entropy, offering a fresh perspective on the deep connections between geometry, quantum mechanics and statistical physics. Developed by Ginestra Bianconi, a mathematical physicist at Queen Mary University of London, UK, and published in Physical Review D, this modified version of gravity provides new quantum information theory insights on the well-established link between statistical mechanics and gravity that is rooted in the thermodynamic properties of black holes.
Quantum relative entropy
At the heart of Bianconiâs theory is the concept of quantum relative entropy (QRE). This is a fundamental concept of information theory, and it quantifies the difference in information encoded in two quantum states. More specifically, QRE is a measure of how much information of one quantum state is carried by another quantum state.
Bianconiâs idea is that the metrics associated with spacetime are quantum operators that encode the quantum state of its geometry. Building on this geometrical insight, she proposes that the action for gravity is the QRE between two different metrics: one defined by the geometry of spacetime and another by the matter fields present within it. In this sense, the theory takes inspiration from John Wheelerâs famous description of gravity: âMatter tells space how to curve, and space tells matter how to move.â However, it also goes further, as it aims to make this relationship explicit in the mathematical formulation of gravity, framing it in a statistical mechanics and information theory action.
Additionally, the theory adapts QRE to the Dirac-Kähler formalism extended to bosons, allowing for a more nuanced understanding of spacetime. The Dirac-Kähler formalism is a geometric reformulation of fermions using differential forms, unifying spinor and tensor descriptions in a coordinate-free way. In simpler terms, it offers an elegant way to describe particles like electrons using the language of geometry and calculus on manifolds.
The role of the G-field
For small energies and low values of spacetime curvature (the âlow couplingâ regime), the equations Bianconi presents reduce to the standard equations of Einsteinâs general theory of relativity. Beyond this regime, the full modified Einstein equations can be written in terms of a new field, the G-field, that gives rise to a non-zero cosmological constant. Often associated with the accelerated expansion of the universe, the cosmological constant contributes to the still-mysterious substance known as dark energy, which is estimated to make up 68% of the mass-energy in the universe. A key feature of Bianconiâs entropy-based theory is that the cosmological constant is actually not constant, but dependent on the G-field. Hence, a key feature of the G-field is that it might provide new insight into what the cosmological constant really is, and where it comes from.
The G-field also has implications for black hole physics. In a follow-up work, Bianconi shows that a common solution in general relativity known as the Schwarzschild metric is an approximation, with the full solution requiring consideration of the G-fieldâs effects.
What does this mean for quantum gravity and cosmology?
The existence of a connection between black holes and entropy also raises the possibility that Bianconiâs framework could shed new light on the black hole information paradox. Since black holes are supposed to evaporate due to Hawking radiation, the paradox addresses the question of whether information that falls into a black hole is truly lost after evaporation. Namely, does a black hole destroy information forever, or is it somehow preserved?
The general theory predicts that the QRE for the Schwarzschild black hole follows the area law, a key feature of black hole thermodynamics, suggesting that further exploration of this framework might lead to new answers about the fundamental nature of black holes.
Unlike other approaches to quantum gravity that are primarily phenomenological, Bianconiâs framework seeks to understand gravity from first principles by linking it directly to quantum information and statistical mechanics. When asked how she became interested in this line of research, she emphasizes the continuity between her previous work on the topology and geometry of higher-order networks, her work on the topological Dirac operator and her current pursuits.
âI was especially struck by a passage in Gian Francesco Giudiceâs recent book Before the Big Bang, where a small girl asks, âIf your book speaks about the universe, does it also speak about me?ââ Bianconi says. âThis encapsulates the idea that new bridges between different scientific domains could be key to advancing our understanding.â
Future directions
There is still much to explore in this approach. In particular, Bianconi hopes to extend this theory into second quantization, where fields are thought of as operators just as physical quantities (position, momentum, so on) are in first quantization. Additionally, the modified Einstein equations derived in this theory have yet to be fully solved, and understanding the full implications of the theory for classical gravity is an ongoing challenge.
Though the research is still in its early stages, Bianconi emphasizes that it could eventually lead to testable hypotheses. The relationship between the theoryâs predicted cosmological constant and experimental measurements, for example, could offer a way to test it against existing data.
Vaire Computing is a start-up seeking to commercialize computer chips based on the principles of reversible computing â a topic Earley studied during her PhD in applied mathematics and theoretical physics at the University of Cambridge, UK. The central idea behind reversible computing is that reversible operations use much less energy, and thus generate much less waste heat, than those in conventional computers.
What skills do you use every day in your job?
In an early-stage start-up environment, you have to wear lots of different hats. Right now, Iâm planning for the next few years, but Iâm also very deep into the engineering side of Vaire, which spans a lot of different areas.
The skill I use most is my ability to jump into a new field and get up to speed with it as quickly as possible, because I cannot claim to be an expert in all the different areas we work in. I cannot be an expert in integrated circuit design as well as developing electronic design automation tooling as well as building better resonators. But what I can do is try to learn about all these things at as deep a level as I can, very quickly, and then guide the people around me with higher-level decisions while also having a bit of fun and actually doing some engineering work.
What do you like best and least about your job?
We have so many great people at Vaire, and being able to talk with them and discuss all the most interesting aspects of their specialities is probably the part I like best. But Iâm also enjoying the fact that in a few years, all this work will culminate in an actual product based on things I worked on when I was in academia. I love theory, and I love thinking about what could be possible in hundreds of yearsâ time, but seeing an idea get closer and closer to reality is great.
The part I have more of a love-hate relationship with is just how intense this job is. Iâm probably intrinsically a workaholic. I donât think Iâve ever had a good balance in terms of how much time I spend on work, whether now or when I was doing my PhD or even before. But when you are responsible for making your company succeed, that degree of intensity becomes unavoidable. It feels difficult to take breaks or to feel comfortable taking breaks, but I hope that as our company grows and gets more structured, that part will improve.
What do you know now that you wish youâd known when you were starting out in your career?
There are so many specifics of what it means to build a computer chip that I wish Iâd known. I may even have suffered a little bit from the DunningâKruger effect [in which people with limited experience of a particular topic overestimate their knowledge] at the beginning, thinking, âI know what a transistor is like. How hard can it be to build a large-scale integrated circuit?â
It turns out itâs very, very hard, and thereâs a lot of complexity around it. When I was a PhD student, it felt like there wasnât that big a gap between theory and implementation. But there is, and while to some extent itâs not possible to know about something until youâve done it, I wish Iâd known a lot more about chip design a few years ago.
The head of the Federal Aviation Administrationâs commercial space transportation office is leaving the agency through a deferred resignation program.
President Trump recognizes the grave threats posed by adversary ballistic and hypersonic missiles and has issued mandates for the Department of Defense to deploy a âGolden Domeâ defense shield for [âŚ]
Quantum transducer A niobium microwave LC resonator (silver) is capacitively coupled to two hybridized lithium niobate racetrack resonators in a paperclip geometry (black) to exchange energy between the microwave and optical domains using the electro-optic effect. (Courtesy: LonÄar group/Harvard SEAS)
The future of quantum communication and quantum computing technologies may well revolve around superconducting qubits and quantum circuits, which have already been shown to improve processing capabilities over classical supercomputers â even when there is noise within the system. This scenario could be one step closer with the development of a novel quantum transducer by a team headed up at the Harvard John A Paulson School of Engineering and Applied Sciences (SEAS).
Realising this future will rely on systems having hundreds (or more) logical qubits (each built from multiple physical qubits). However, because superconducting qubits require ultralow operating temperatures, large-scale refrigeration is a major challenge â there is no technology available today that can provide the cooling power to realise such large-scale qubit systems.
Superconducting microwave qubits are a promising option for quantum processor nodes, but they currently require bulky microwave components. These components create a lot of heat that can easily disrupt the refrigeration systems cooling the qubits.
One way to combat this cooling conundrum is to use a modular approach, with small-scale quantum processors connected via quantum links, and each processor having its own dilution refrigerator. Superconducting qubits can be accessed using microwave photons between 3 and 8 GHz, thus the quantum links could be used to transmit microwave signals. The downside of this approach is that it would require cryogenically cooled links between each subsystem.
On the other hand, optical signals at telecoms frequency (around 200âTHz) can be generated using much smaller form factor components, leading to lower thermal loads and noise, and can be transmitted via low-loss optical fibres. The transduction of information between optical and microwave frequencies is therefore key to controlling superconducting microwave qubits without the high thermal cost.
The large energy gap between microwave and optical photons makes it difficult to control microwave qubits with optical signals and requires a microwaveâoptical quantum transducer (MOQT). These MOQTs provide a coherent, bidirectional link between microwave and optical frequencies while preserving the quantum states of the qubit. A team led by SEAS researcher Marko LonÄar has now created such a device, describing it in Nature Physics.
LonÄar and collaborators have developed a thin-film lithium niobate (TFLN) cavity electro-optic (CEO)-based MOQT (clad with silica to aid thermal dissipation and mitigate optical losses) that converts optical frequencies into microwave frequencies with low loss. The team used the CEO-MOQT to facilitate coherent optical driving of a superconducting qubit (controlling the state of the quantum system by manipulating its energy).
The on-chip transducer system contains three resonators: a microwave LC resonator capacitively coupled to two optical resonators using the electro-optic effect. The device creates hybridized optical modes in the transducer that enables a resonance-enhanced exchange of energy between the microwave and optical modes.
The transducer uses a process known as difference frequency generation to create a new frequency output from two input frequencies. The optical modes â an optical pump in a classical red-pumping regime and an optical idler â interact to generate a microwave signal at the qubit frequency, in the form of a shaped, symmetric single microwave photon.
This microwave signal is then transmitted from the transducer to a superconducting qubit (in the same refrigerator system) using a coaxial cable. The qubit is coupled to a readout resonator that enables its state to be read by measuring the transmission of a readout pulse.
The MOQT operated with a peak conversion efficiency of 1.18% (in both microwave-to-optical and optical-to-microwave regimes), low microwave noise generation and the ability to drive Rabi oscillations in a superconducting qubit. Because of the low noise, the researchers state that stronger optical-pump fields could be used without affecting qubit performance.
Having effectively demonstrated the ability to control superconducting circuits with optical light, the researchers suggest a number of future improvements that could increase the device performance by orders of magnitude. For example, microwave and optical coupling losses could be reduced by fabricating a single-ended microwave resonator directly onto the silicon wafer instead of on silica. A flux tuneable microwave cavity could increase the optical bandwidth of the transducer. Finally, the use of improved measurement methods could improve control of the qubits and allow for more intricate gate operations between qubit nodes.
The researchers suggest this type of device could be used for networking superconductor qubits when scaling up quantum systems. The combination of this work with other research on developing optical readouts for superconducting qubit chips âprovides a path towards forming all-optical interfaces with superconducting qubitsâŚto enable large scale quantum processors,â they conclude.
The proposal includes $25 billion for the "Golden Dome" next-generation missile defense initiative, with about $15 billion allocated to satellites, sensors, space-base interceptors and launch infrastructure.
Astrotech, a Lockheed Martin subsidiary, is the primary provider of payload storage and satellite-processing services for spacecraft at both Eastern and Western ranges.
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China approved international requests, including from two U.S. universities, to borrow small portions of moon samples collected by its Changâe-5 mission.
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Nonlocal correlations that define quantum entanglement could be reconciled with Einsteinâs theory of relativity if spaceâtime had two temporal dimensions. That is the implication of new theoretical work that extends nonlocal hidden variable theories of quantum entanglement and proposes a potential experimental test.
Marco Pettini, a theoretical physicist at Aix Marseille University in France, says the idea arose from conversations with the mathematical physicist Roger Penrose â who shared the 2020 Nobel Prize for Physics for showing that the general theory of relativity predicted black holes. âHe told me that, from his point of view, quantum entanglement is the greatest mystery that we have in physics,â says Pettini. The puzzle is encapsulated by Bellâs inequality, which was derived in the mid-1960s by the Northern Irish physicist John Bell.
Bellâs breakthrough was inspired by the 1935 EinsteinâPodolskyâRosen paradox, a thought experiment in which entangled particles in quantum superpositions (using the language of modern quantum mechanics) travel to spatially separated observers Alice and Bob. They make measurements of the same observable property of their particles. As they are superposition states, the outcome of neither measurement is certain before it is made. However, as soon as Alice measures the state, the superposition collapses and Bobâs measurement is now fixed.
Quantum scepticism
A sceptic of quantum indeterminacy could hypothetically suggest that the entangled particles carried hidden variables all along, so that when Alice made her measurement, she simply found out the state that Bob would measure rather than actually altering it. If the observers are separated by a distance so great that information about the hidden variableâs state would have to travel faster than light between them, then hidden variable theory violates relativity. Bell derived an inequality showing the maximum degree of correlation between the measurements possible if each particle carried such a âlocalâ hidden variable, and showed it was indeed violated by quantum mechanics.
A more sophisticated alternative investigated by the theoretical physicists David Bohm and his student Jeffrey Bub, as well as by Bell himself, is a nonlocal hidden variable. This postulates that the particle â including the hidden variable â is indeed in a superposition and defined by an evolving wavefunction. When Alice makes her measurement, this superposition collapses. Bobâs value then correlates with Aliceâs. For decades, researchers believed the wavefunction collapse could travel faster than light without allowing superliminal exchange of information â therefore without violating the special theory of relativity. However, in 2012 researchers showed that any finite-speed collapse propagation would enable superluminal information transmission.
âI met Roger Penrose several times, and while talking with him I asked âWell, why couldnât we exploit an extra time dimension?â,â recalls Pettini. Particles could have five-dimensional wavefunctions (three spatial, two temporal), and the collapse could propagate through the extra time dimension â allowing it to appear instantaneous. Pettini says that the problem Penrose foresaw was that this would enable time travel, and the consequent possibility that one could travel back through the âextra timeâ to kill oneâs ancestors or otherwise violate causality. However, Pettini says he ârecently found in the literature a paper which has inspired some relatively standard modifications of the metric of an enlarged spaceâtime in which massive particles are confined with respect to the extra time dimensionâŚSince we are made of massive particles, we donât see it.â
Toy model
Pettini believes it might be possible to test this idea experimentally. In a new paper, he proposes a hypothetical experiment (which he describes as a toy model), in which two sources emit pairs of entangled, polarized photons simultaneously. The photons from one source are collected by recipients Alice and Bob, while the photons from the other source are collected by Eve and Tom using identical detectors. Alice and Eve compare the polarizations of the photons they detect. Aliceâs photon must, by fundamental quantum mechanics, be entangled with Bobâs photon, and Eveâs with Tomâs, but otherwise simple quantum mechanics gives no reason to expect any entanglement in the system.
Pettini proposes, however, that Alice and Eve should be placed much closer together, and closer to the photon sources, than to the other observers. In this case, he suggests, the communication of entanglement through the extra time dimension when the wavefunction of Aliceâs particle collapses, transmitting this to Bob, or when Eveâs particle is transmitted to Tom would also transmit information between the much closer identical particles received by the other woman. This could affect the interference between Aliceâs and Eveâs photons and cause a violation of Bellâs inequality. â[Alice and Eve] would influence each other as if they were entangled,â says Pettini. âThis would be the smoking gun.â
Bub, now a distinguished professor emeritus at the University of Maryland, College Park, is not holding his breath. âIâm intrigued by [Pettini] exploiting my old hidden variable paper with Bohm to develop his two-time model of entanglement, but to be frank I canât see this going anywhere,â he says. âI donât feel the pull to provide a causal explanation of entanglement, and I donât any more think of the âcollapseâ of the wave function as a dynamical process.â He says the central premise of Pettiniâs â that adding an extra time dimension could allow the transmission of entanglement between otherwise unrelated photons, is âa big leapâ. âPersonally, I wouldnât put any money on it,â he says.
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