Depth-Bounded Quantum Cryptography with Applications to One-Time Memory and More

With the power of quantum information, we can achieve exciting and classically impossible cryptographic primitives. However, almost all quantum cryptography faces extreme difficulties with the near-term intermediate-scale quantum technology (NISQ technology); namely, the short lifespan of quantum states and limited sequential computation. At the same time, considering only limited quantum adversaries may still enable us to achieve never-before-possible tasks. In this work, we consider quantum cryptographic primitives against limited quantum adversaries - depth-bounded adversaries. We introduce a model for (depth-bounded) NISQ computers, which are classical circuits interleaved with shallow quantum circuits. Then, we show one-time memory can be achieved against any depth-bounded quantum adversaries introduced in the work, with their depth being any pre-fixed polynomial. Therefore we obtain applications like one-time programs and one-time proofs. Finally, we show our one-time memory has correctness even against constant-rate errors

Beating Classical Impossibility of Position Verification

Chandran et al. (SIAM J. Comput. \u2714) formally introduced the cryptographic task of position verification, where they also showed that it cannot be achieved by classical protocols. In this work, we initiate the study of position verification protocols with classical verifiers. We identify that proofs of quantumness (and thus computational assumptions) are necessary for such position verification protocols. For the other direction, we adapt the proof of quantumness protocol by Brakerski et al. (FOCS \u2718) to instantiate such a position verification protocol. As a result, we achieve classically verifiable position verification assuming the quantum hardness of Learning with Errors. Along the way, we develop the notion of 1-of-2 non-local soundness for a natural non-local game for 1-of-2 puzzles, first introduced by Radian and Sattath (AFT \u2719), which can be viewed as a computational unclonability property. We show that 1-of-2 non-local soundness follows from the standard 2-of-2 soundness (and therefore the adaptive hardcore bit property), which could be of independent interest

Hidden Cosets and Applications to Unclonable Cryptography

In this work, we study a generalization of hidden subspace states to hidden coset states (first introduced by Aaronson and Christiano [STOC '12]). This notion was considered independently by Vidick and Zhang [Eurocrypt '21], in the context of proofs of quantum knowledge from quantum money schemes. We explore unclonable properties of coset states and several applications: - We show that assuming indistinguishability obfuscation (iO), hidden coset states possess a certain direct product hardness property, which immediately implies a tokenized signature scheme in the plain model. Previously, it was known only relative to an oracle, from a work of Ben-David and Sattath [QCrypt '17]. - Combining a tokenized signature scheme with extractable witness encryption, we give a construction of an unclonable decryption scheme in the plain model. The latter primitive was recently proposed by Georgiou and Zhandry [ePrint '20], who gave a construction relative to a classical oracle. - We conjecture that coset states satisfy a certain natural (information-theoretic) monogamy-of-entanglement property. Assuming this conjecture is true, we remove the requirement for extractable witness encryption in our unclonable decryption construction, by relying instead on compute-and-compare obfuscation for the class of unpredictable distributions. This conjecture was later proved by Culf and Vidick in a follow-up work. - Finally, we give a construction of a copy-protection scheme for pseudorandom functions (PRFs) in the plain model. Our scheme is secure either assuming iO, OWF, and extractable witness encryption, or assuming iO, OWF, compute-and-compare obfuscation for the class of unpredictable distributions, and the conjectured monogamy property mentioned above. This is the first example of a copy-protection scheme with provable security in the plain model for a class of functions that is not evasive.Comment: Minor update

MUSIC Algorithm for IRS-Assisted AOA Estimation

Based on the signals received across its antennas, a multi-antenna base station (BS) can apply the classic multiple signal classification (MUSIC) algorithm for estimating the angle of arrivals (AOAs) of its incident signals. This method can be leveraged to localize the users if their line-of-sight (LOS) paths to the BS are available. In this paper, we consider a more challenging AOA estimation setup in the intelligent reflecting surface (IRS) assisted integrated sensing and communication (ISAC) system, where LOS paths do not exist between the BS and the users, while the users' signals can be transmitted to the BS merely via their LOS paths to the IRS as well as the LOS path from the IRS to the BS. Specifically, we treat the IRS as the anchor and are interested in estimating the AOAs of the incident signals from the users to the IRS. Note that we have to achieve the above goal based on the signals received by the BS, because the passive IRS cannot process its received signals. However, the signals received across different antennas of the BS only contain AOA information of its incident signals via the LOS path from the IRS to the BS. To tackle this challenge arising from the spatial-domain received signals, we propose an innovative approach to create temporal-domain multi-dimension received signals for estimating the AOAs of the paths from the users to the IRS. Specifically, via a proper design of the user message pattern and the IRS reflecting pattern, we manage to show that our designed temporal-domain multi-dimension signals can be surprisingly expressed as a function of the virtual steering vectors of the IRS towards the users. This amazing result implies that the classic MUSIC algorithm can be applied to our designed temporal-domain multi-dimension signals for accurately estimating the AOAs of the signals from the users to the IRS.Comment: to appear in IEEE VTC 2023-Fal

CORRELATIONS OF POSTURAL CONTROL TO PROPRIOCEPTION, TACTILE SENSATION AND MUSCLE STRENGTH AMONG OLDER ADULTS

Background: Falls are one of the most important causes of physical injury and death in older adults. Postural control is associated with an elevated risk of falls in older adults. the purpose of this study was to assess the correlation between static/dynamic postural control ability and proprioception, plantar skin touch, and muscle strength in older adults. Method: Partial correlation analysis was used to quantitatively analyze the correlation between plantar tactile sensitivity, proprioception, lower limb muscle strength and postural control, and regression analysis was used to build an effective model of human postural control. Result: The postural control of the older adults is related to the plantar tactile sensitivity, proprioception, and lower limb muscle strength. Conclusion: dynamic postural control mainly affected by lower limb muscle strength and proprioception, suggesting that trainings to improve the ankle plantarflexion, hip abduction muscle strength and knee and ankle proprioception should be recommended to older adults to improve dynamic postural control. Static postural control mainly affected by planter tactile sensitivity and proprioception suggesting that trainings to improve the proprioception and planter tactile sensitivity should be recommended to older adults to improve static postural control

Self-healing metal coordinated hydrogels using nucleotide ligands

A supramolecular gel formed by coordination of Zn2+ with adenosine monophosphate (AMP) is reported. The adenine base, the monophosphate, and Zn2+ are all important for gel formation. Mechanically disrupted gels can re-form upon centrifugation; applications of this gel for guest-molecule entrapment are explored.Beijing Higher Education Young Elite Teacher Project || ETP0520 Fundamental Research Funds for the Central Universities || YS1407 China Scholarship Council || Natural Sciences and Engineering Research Council |

Classical vs Quantum Advice and Proofs under Classically-Accessible Oracle

It is a long-standing open question to construct a classical oracle relative to which BQP/qpoly $\neq$ BQP/poly or QMA $\neq$ QCMA. In this paper, we construct classically-accessible classical oracles relative to which BQP/qpoly $\neq$ BQP/poly and QMA $\neq$ QCMA. Here, classically-accessible classical oracles are oracles that can be accessed only classically even for quantum algorithms. Based on a similar technique, we also show an alternative proof for the separation of QMA and QCMA relative to a distributional quantumly-accessible classical oracle, which was recently shown by Natarajan and Nirkhe.Comment: 31 pages. Added classically-accessible classical oracle separation of QMA and QCMA and updated the abstrac