Near-term Technology Research Articles

Connecting quantum cities: simulation of a satellite-based quantum network

We present and analyze an architecture for a European-scale quantum network using satellite links to connect Quantum Cities, which are metropolitan quantum networks with minimal hardware requirements for the end users. Using NetSquid, a quantum network simulation tool based on discrete events, we assess and benchmark the performance of such a network linking distant locations in Europe in terms of quantum key distribution rates, considering realistic parameters for currently available or near-term technology. Our results highlight the key parameters and the limits of current satellite quantum communication links and can be used to assist the design of future missions. We also discuss the possibility of using high-altitude balloons as an alternative to satellites.

Pathways to Decarbonization of Deep-Sea Shipping: An Aframax Case Study

Deep-sea decarbonization remains an enigma as the world scrambles to reduce global emissions. This study looks at near-term decarbonization solutions for deep-sea shipping. Pathways are defined, which are appealing to ship owners and major world economies alike. The economic and environmental viability of several of the most advanced near-term technologies for deep-sea decarbonization are revealed. The environmental analysis suggests the necessity of new emission intensity metrics. The economic analysis indicates that the carbon tax could be a great motivator to invest in decarbonization technologies. Standalone decarbonization technologies can provide a maximum of 20% emissions reduction. Hence, to meet IMO 2050 targets of 50% emissions reduction, several solutions need to be utilized in tandem. This study reaches the conclusion that alternative fuels are the crucial step to achieve a net zero carbon economy, although bunkering, infrastructure, and economic hurdles need to be overcome for the widespread implementation of carbon-neutral fuels.

Should we embrace “Big Sister”? Smart speakers as a means to combat intimate partner violence

It is estimated that one in three women experience intimate partner violence (IPV) across the course of their life. The popular uptake of “smart speakers” powered by sophisticated AI means that surveillance of the domestic environment is increasingly possible. Correspondingly, there are various proposals to use smart speakers to detect or report IPV. In this paper, we clarify what might be possible when it comes to combatting IPV using existing or near-term technology and also begin the project of evaluating this project both ethically and politically. We argue that the ethical landscape looks different depending on whether one is considering the decision to develop the technology or the decision to use it once it has been developed. If activists and governments wish to avoid the privatisation of responses to IPV, ubiquitous surveillance of domestic spaces, increasing the risk posed to members of minority communities by police responses to IPV, and the danger that more powerful smart speakers will be co-opted by men to control and abuse women, then they should resist the development of this technology rather than wait until these systems are developed. If it is judged that the moral urgency of IPV justifies exploring what might be possible by developing this technology, even in the face of these risks, then it will be imperative that victim-survivors from a range of demographics, as well as government and non-government stakeholders, are engaged in shaping this technology and the legislation and policies needed to regulate it.

Resource-efficient simulation of noisy quantum circuits and application to network-enabled QRAM optimization

Giovannetti, Lloyd, and Maccone (2008) proposed a quantum random access memory (QRAM) architecture to retrieve arbitrary superpositions of N (quantum) memory cells via quantum switches and O(log (N)) address qubits. Toward physical QRAM implementations, Chen et al. (2021) recently showed that QRAM maps natively onto optically connected quantum networks with O(log (N)) overhead and built-in error detection. However, modeling QRAM on large networks has been stymied by exponentially rising classical compute requirements. Here, we address this bottleneck by: (1) introducing a resource-efficient method for simulating large-scale noisy entanglement, allowing us to evaluate hundreds and even thousands of qubits under various noise channels; and (2) analyzing Chen et al.’s network-based QRAM as an application at the scale of quantum data centers or near-term quantum internet; and (3) introducing a modified network-based QRAM architecture to improve quantum fidelity and access rate. We conclude that network-based QRAM could be built with existing or near-term technologies leveraging photonic integrated circuits and atomic or atom-like quantum memories.

Demonstration of quantum-digital payments

Digital payments have replaced physical banknotes in many aspects of our daily lives. Similarly to banknotes, they should be easy to use, unique, tamper-resistant and untraceable, but additionally withstand digital attackers and data breaches. Current technology substitutes customers’ sensitive data by randomized tokens, and secures the payment’s uniqueness with a cryptographic function, called a cryptogram. However, computationally powerful attacks violate the security of these functions. Quantum technology comes with the potential to protect even against infinite computational power. Here, we show how quantum light can secure daily digital payments by generating inherently unforgeable quantum cryptograms. We implement the scheme over an urban optical fiber link, and show its robustness to noise and loss-dependent attacks. Unlike previously proposed protocols, our solution does not depend on long-term quantum storage or trusted agents and authenticated channels. It is practical with near-term technology and may herald an era of quantum-enabled security.

Risk trade-space analysis for safe human expeditions to Mars

We assessed the integrated safety, health, and performance risk to crews on long-duration missions, specifically to Mars. Using a systems approach rather than one focused on individual countermeasures, we examined the trade space around several such risks to identify high-potential risk mitigation strategies and characterize aspects of Mars mission architectures that could lower aggregated risk. Current Mars Design Reference missions would require durations well over two years and would increase crew exposure to radiation and microgravity well beyond ISS levels, likely resulting in significantly reduced performance beyond our current capability to mitigate that could jeopardize mission success. A “fast Mars transit” round-trip mission concept was studied using an innovative flight dynamics approach to quantify the minimum total mission energy required for a Mars transit with total mission duration less than 400 days. This approach holds promise for sending humans to Mars and returning them safely with acceptable, potentially mitigatable, exposure to microgravity and radiation using current or near-term technologies. The fast transit concept would also result in fewer time-driven vehicle failures and enable sustainable deployment of humans and infrastructure to Mars on a regular cadence, allowing steady exploration and colonization of Mars. Finally, we conclude that reliance on the Low Earth Orbit (LEO) mission operations paradigm – i.e., one of near-complete real-time dependence on experts at Mission Control to manage the combined state of the mission, vehicle, and crew – is high risk given the communication delays and limited resupply of any Mars mission, and this risk is not eliminated by the shorter missions durations of fast transit scenarios. Based on historical trends, it is highly likely that the crew will face a high-consequence problem of uncertain origin during Mars transit when ground support will be greatly reduced. While it may be possible to reduce anomaly rates through improved reliability analysis and testing, and to reduce anomaly impacts through added robustness, such mitigations address only known failure modes and known uncertainties. Therefore, a radical shift in the Human-Systems Integration Architecture (HSIA) that defines the operational paradigm, systems design, and human-systems interactions is required to improve the risk posture to an acceptable level regardless of mission duration.

Project Lyra: A mission to 1I/’Oumuamua without Solar Oberth Manoeuvre

To settle the question of the nature of the interstellar object 1I/’Oumuamua requires in-situ observations via a spacecraft, as the object is already out of range of existing telescopes. Most previous proposals for reaching 1I/’Oumuamua using near-term technologies are based on the Solar Oberth Manoeuvre (SOM), as trajectories without the SOM are generally significantly inferior in terms of lower mission duration and higher total velocity requirement. While the SOM allows huge velocity gains, it is also technically challenging and thereby increases programmatic and mission-related risks. In this paper, we identify an alternative route to the interstellar object 1I/’Oumuamua, based on a launch in 2028, which does not require a SOM but has a similar performance as missions with a SOM. It instead employs a Jupiter Oberth Manoeuvre (JOM) with a total time of flight of around 26 years or so. The efficacy of this trajectory is a result of it significantly reducing the ΔV to Jupiter by exploiting the VEEGA sequence. The total ΔV of the trajectory is 15.8 kms−1 and the corresponding payload mass is 115 kg for a SLS Block 1B or 241 kg for a Block 2. A further advantage of the JOM is that the arrival speed relative to 1I/’Oumuamua is approximately 18 kms−1, much lower than the equivalent for the SOM of around 30 kms−1.

Quantum-enhanced radiometry via approximate quantum error correction

Quantum sensing based on exotic quantum states is appealing for practical metrology applications and fundamental studies. However, these quantum states are vulnerable to noise and the resulting quantum enhancement is weakened in practice. Here, we experimentally demonstrate a quantum-enhanced sensing scheme with a bosonic probe, by exploring the large Hilbert space of the bosonic mode and developing both the approximate quantum error correction and the quantum jump tracking approaches. In a practical radiometry scenario, we attain a 5.3 dB enhancement of sensitivity, which reaches 9.1 × 10−4 Hz−1/2 when measuring the excitation population of a receiver mode. Our results demonstrate the potential of quantum sensing with near-term quantum technologies, not only shedding new light on the quantum advantage of sensing, but also stimulating further efforts on bosonic quantum technologies.

High-fidelity magic-state preparation with a biased-noise architecture

Magic state distillation is a resource intensive subroutine that consumes noisy input states to produce high-fidelity resource states that are used to perform logical operations in practical quantum-computing architectures. The resource cost of magic state distillation can be reduced by improving the fidelity of the raw input states. To this end, we propose an initialization protocol that offers a quadratic improvement in the error rate of the input magic states in architectures with biased noise. This is achieved by preparing an error-detecting code which detects the dominant errors that occur during state preparation. We obtain this advantage by exploiting the native gate operations of an underlying qubit architecture that experiences biases in its noise profile. We perform simulations to analyze the performance of our protocol with the XZZX surface code. Even at modest physical parameters with a two-qubit gate error rate of $0.7\%$ and total probability of dominant errors in the gate $O(10^3)$ larger compared to that of non-dominant errors, we find that our preparation scheme delivers magic states with logical error rate $O(10^{-8})$ after a single round of the standard 15-to-1 distillation protocol; two orders of magnitude lower than using conventional state preparation. Our approach therefore promises considerable savings in overheads with near-term technology.

Current State of Pleural-Directed Adjuncts Against Malignant Pleural Mesothelioma.

Multimodality therapy including surgical resection is the current paradigm in treating malignant pleural mesothelioma (MPM), a thoracic surface cancer without cure. The main limitation of all surgical approaches is the lack of long-term durability because macroscopic complete resection (R1 resection) commonly predisposes to locoregional relapse. Over the years, there have been many studies that describe various intrapleural strategies that aim to extend the effect of surgical resection. The majority of these approaches are intraoperative adjuvants. Broadly, there are three therapeutic classes that employ diverse agents. The most common, widely used group of adjuvants are comprised of direct therapeutics such as intracavitary chemotherapy (± hyperthermia). By comparison, the least commonly employed intrathoracic adjuvant is the class comprised of drug-device combinations like photodynamic therapy (PDT). But the most rapidly evolving (new) class with much potential for improved efficacy are therapeutics delivered by specialized drug vehicles such as a fibrin gel containing cisplatin. This review provides an updated perspective on pleural-directed adjuncts in the management of MPM as well as highlighting the most promising near-term technology breakthroughs.

Interstellar Now! Missions to Explore Nearby Interstellar Objects

The recently discovered first high velocity hyperbolic objects passing through the Solar System, 1I/'Oumuamua and 2I/Borisov, have raised the question about near term missions to Interstellar Objects. In situ spacecraft exploration of these objects will allow the direct determination of both their structure and their chemical and isotopic composition, enabling an entirely new way of studying small bodies from outside our solar system. In this paper, we map various Interstellar Object classes to mission types, demonstrating that missions to a range of Interstellar Object classes are feasible, using existing or near-term technology. We describe flyby, rendezvous and sample return missions to interstellar objects, showing various ways to explore these bodies characterizing their surface, dynamics, structure and composition. Interstellar objects likely formed very far from the solar system in both time and space; their direct exploration will constrain their formation and history, situating them within the dynamical and chemical evolution of the Galaxy. These mission types also provide the opportunity to explore solar system bodies and perform measurements in the far outer solar system.

Theoretical methods to design and test quantum simulators for the compact Abelian Higgs model

The lattice compact Abelian Higgs model is a non-perturbative regularized formulation of low-energy scalar quantum electrodynamics. In 1+1 dimensions, this model can be quantum simulated using a ladder-shaped optical lattice with Rydberg-dressed atoms (Zhang et al., Phys. Rev. Lett. 121, 223201). In this setup, one spatial dimension is used to carry the angular momentum of the quantum rotors. One can use truncations corresponding to spin-2 and spin-1 to build local Hilbert spaces associated with the links of the lattice. We argue that ladder-shaped configurable arrays of Rydberg atoms can be used for the same purpose. We make concrete proposals involving two and three Rydberg atoms to build one local spin-1 space (a qutrit). We show that the building blocks of the Hamiltonian calculations are models with one and two spins. We compare target and simulators using perturbative and numerical methods. The two-atom setup provides an easily controllable simulator of the one-spin model while the three-atom setup involves solving nonlinear equations. This could be tested with current technology. We argue that near-term technology could be used to quantum simulate models with two or more spins.

Non-Markovian memory strength bounds quantum process recoverability

Generic non-Markovian quantum processes have infinitely long memory, implying an exact description that grows exponentially in complexity with observation time. Here, we present a finite memory ansatz that approximates (or recovers) the true process with errors bounded by the strength of the non-Markovian memory. The introduced memory strength is an operational quantity and depends on the way the process is probed. Remarkably, the recovery error is bounded by the smallest memory strength over all possible probing methods. This allows for an unambiguous and efficient description of non-Markovian phenomena, enabling compression and recovery techniques pivotal to near-term technologies. We highlight the implications of our results by analyzing an exactly solvable model to show that memory truncation is possible even in a highly non-Markovian regime.

Sending a spacecraft to interstellar comet 2I/Borisov

On 2019 August 30, a second interstellar object 2I/Borisov was discovered 2 years after the discovery of the first known interstellar object, 1I/’Oumuamua. Can we send a spacecraft to this object, using existing and near-term technologies? In this paper we assess the technical feasibility of a near-term mission to 2I/Borisov. We apply the Optimum Interplanetary Trajectory Software (OITS) tool to generate trajectories to 2I/Borisov. As results, we get the minimal ΔV trajectory with a launch date in 2018 July. For this trajectory, a Falcon Heavy launcher could have hauled an 8 ton spacecraft to 2I/Borisov. For a later launch date, results for a combined powered Jupiter flyby with a Solar Oberth maneuver are presented. For a launch in 2027, we could reach 2I/Borisov in 2052, using the Space Launch System (SLS), up-scaled Parker probe heat shield technology, and solid propulsion engines. Using a SLS a spacecraft with a mass of 765 kg could be sent to 2I/Borisov. A Falcon Heavy could deliver 202 kg to 2I/Borisov. Arrival times sooner than 2052 can potentially be achieved but with higher ΔV requirements and lower spacecraft payload masses. 2I/Borisov’s discovery shortly after the discovery of 1I/’Oumuamua implies that the next interstellar object might be discovered in the near future. The feasibility of a mission to both, 1I/’Oumuamua and 2I/Borisov using scaled versions of existing technologies indicates that missions to at least some future interstellar objects are feasible as well.

Proposal for space-borne quantum memories for global quantum networking

Global-scale quantum communication links will form the backbone of the quantum internet. However, exponential loss in optical fibres precludes any realistic application beyond few hundred kilometres. Quantum repeaters and space-based systems offer solutions to overcome this limitation. Here, we analyse the use of quantum memory (QM)-equipped satellites for quantum communication focussing on global range repeaters and memory-assisted (MA-) QKD, where QMs help increase the key rate by synchronising otherwise probabilistic detection events. We demonstrate that satellites equipped with QMs provide three orders of magnitude faster entanglement distribution rates than existing protocols based on fibre-based repeaters or space systems without QMs. We analyse how entanglement distribution performance depends on memory characteristics, determine benchmarks to assess the performance of different tasks and propose various architectures for light-matter interfaces. Our work provides a roadmap to realise unconditionally secure quantum communications over global distances with near-term technologies.

Forecasting Technology Trends through the Gap Between Science and Technology: The Case of Software as an E-Commerce Service

Identifying technology trends can be a key success factor for companies to be competitive and take advantage of technological trends before they occur. The companies always work to plan for future products and services. For that, it is important to turn to methods that are used for technology forecasting. These tools help the companies to define potential markets for innovative new products and services. This paper uses text mining techniques along with expert judgment to detect and analyze the near-term technology evolution trends in a Software as a Service (SaaS) case study. The longer-term technology development trend in this case is forecasted by analyzing the gaps between science and technology. This paper contributes to the technology forecasting methodology and will be of interest to those in SaaS technology. Our findings reveal five trends in the technology: 1) virtual networking, 2) the hybrid cloud, 3) modeling methodologies, 4) mobile applications, and 5) web applications. Among the results achieved, we can summarize the interesting ones as follows: it is possible to say that traditional information systems are now evolving into online information systems. On the other hand, the use of a licensing model based on subscriptions triggers the change in perpetual licensing models. The product range that has evolved towards mobile technologies has put pressure on information storage technologies and has led to the search for new methods especially in the development of database systems.

Space Nuclear Propulsion Fuel and Moderator Development Plan Conceptual Testing Reference Design

As future U.S. National Aeronautics and Space Administration (NASA) missions aim for destinations farther out into the solar system, space nuclear propulsion (SNP), and in particular nuclear thermal propulsion (NTP), is the only feasible near-term technology able to provide specific impulses of 900 s or greater and thrust in the range of tens of thousands of pounds. To maximize the success of the SNP program as a whole, a Fuel and Moderator Development Plan (FMDP) was created to mature mission critical technology, such as the reactor fuel form and moderator material. This technical note details the conceptual testing reference design that provides the basis for the FMDP for future design and testing activities to meet NASA’s goals. Through this work BWX Technologies, Inc. and its subsidiaries, referred to as BWXT, continue to be an integral part of government space nuclear programs and has historically been a part of major design, manufacturing, and testing developments. As an example, during the 1990s BWXT supported fuel development for the Space NTP (SNTP) program, an advanced technology development effort aimed at providing the nation with a new and dramatically higher performing rocket engine that would more than double the performance of the best conventional chemical rocket engines. Since 2017, BWXT has been participating in the NASA SNP program for the low-enrichment uranium NTP rocket engine as part of its Game Changing Development feasibility conceptual design program and now more recently Technology Demonstration Mission.

Near-term self-replicating probes - A concept design

Self-replicating probes are spacecraft with the capacity to create copies of themselves. Self-replication would potentially allow for an exponential increase in the number of probes and thereby drastically improve the efficiency of space exploration. Despite this potential, an integrated assessment of self-replicating space probes has not been presented since the 1980s, and it is still unclear how far they are feasible. In this paper, we propose a concept for a partially self-replicating probe for space exploration based on current and near-term technologies, with a focus on small spacecraft. The purpose is to chart a path towards self-replication with near-term benefits, rather than attempting full self-replication. For this reason, components such as microchips and other microelectronic components are brought with the initial probe and are not replicated. We estimate that such a probe would be capable of replicating 70% of its mass. To further increase this percentage, we identify technology gaps which may be usefully addressed. We conclude that small-scale, partially self-replicating probes are feasible near-term. Their benefits would become significant in exploration missions requiring in the order of a dozen of probes.

Modeling the External Effects of Air Taxis in Reducing the Energy Consumption of Road Traffic

Air taxis are currently being demonstrated. Few studies have quantified their external effects in reducing on-road vehicle fuel consumption. The hypothesis of this paper is that air taxis may divert some drivers away from congested traffic corridors, improve traffic speed and fuel economy, and reduce congestion-induced energy consumption. A model is developed that links several key components: mode choice, the relationship between travel demand and traffic speeds, the relationship between traffic speeds and fuel economies, and the heterogenous value of travel time. It is applied to the route from downtown Los Angeles to Los Angeles International Airport, where at peak hours 38,200 vehicles attempt to use the route that has an hourly capacity of 17,200 vehicles. The model estimates that, with conservative assumptions and near-term technologies, diverting 3.2% of the traffic to air taxis could produce a 15% reduction in traffic vehicle fuel use. With optimistic assumptions and mature technologies, the study estimates that diverting 20% of traffic could reduce the traffic vehicle fuel use by about 74%. The key insight is that if a small share of congested travelers switched to air taxis, motivated by private benefits of time savings, significant external benefits for other road travelers (time savings and fuel savings) and to society (reduced energy use and emissions), would ensue creating a win-win-win outcome. These estimates (which are not intended as predictions because of the stated limitations) strongly suggest the need to consider the external energy effect in future cost-benefit analyses of air taxi technologies.

Consolidated design of the HCPB Breeding Blanket for the pre-Conceptual Design Phase of the EU DEMO and harmonization with the ITER HCPB TBM program

Abstract From 2014 to 2020, the Pre-Conceptual Design phase (PCD) of the EU DEMO has taken place. The activities in the PCD phase differ from past exercises in their strong Systems Engineering methodology, as well as for the pragmatic approach in their technology choices. The Helium Cooled Pebble Bed (HCPB) is one of the 2 candidates as driver blanket for the EU DEMO in the PCD phase. Several design iterations have been required during the PCD phase in order to adjust the design to the current demanding DEMO requirements, to the very challenging systems integration and to the need to keep near-term technologies. To this respect, the design has evolved to a so-called fuel-breeder pin architecture built in single-module segments. The pins are filled with a pebble bed of a ceramic breeder mixture of Li4SiO4 + 35 mol % Li2TiO3 (60% 6Li) and are embedded in prismatic blocks of Be12Ti acting as neutron multiplier. He gas at 8 MPa is used as coolant with a temperature window of 300–520 °C. This architecture has proven to achieve a large tritium breeding performance (≈1.20), a remarkably low plant circulating power (