We propose a method to characterize the features of a cold strontium cloud in a magneto-optical trap(MOT)through the photoionization of cold Sr atoms in a custom-designed reaction microscope.Sr atoms in the dark state...We propose a method to characterize the features of a cold strontium cloud in a magneto-optical trap(MOT)through the photoionization of cold Sr atoms in a custom-designed reaction microscope.Sr atoms in the dark state of 5s5p3P2 populated via the cascade transition 5s5p^(1)P_(1)→5s4d^(1)D_(2)→5s5p^(3)P_(2)accumulate a significant fraction,giving a long lifetime of 520 s.These atoms in the dark state are subsequently trapped by the gradient magnetic field of the MOT.By scanning the Sr+momentum distributions ionized with an 800 nm infrared femtosecond laser,we are able to outline the size of~0.55 mm in radius and the temperature of~0.40 mK for the dark-state atoms,which is significantly cooler than the MOT temperature of 3.3 mK trapped in the 461 nm.The size of MOT exhibits an oblate spheroidal distribution with a radius of approximately 0.35 mm and 0.55 mm,extracted with momenta of photoion and absorption imaging,respectively.The results using the photoion momenta are consistent with the expected results from absorption imaging,which confirms the method's reliability.The advantage of this method is the ability to simultaneously characterize the distribution information of atoms in different initial states within the cold atomic cloud.展开更多
SPHINCS+is a hash-based digital signature scheme that has been selected for post-quantum cryptography(PQC)standardization announced by the U.S.National Institute of Standards and Technology(NIST)in 2022.Although SPHIN...SPHINCS+is a hash-based digital signature scheme that has been selected for post-quantum cryptography(PQC)standardization announced by the U.S.National Institute of Standards and Technology(NIST)in 2022.Although SPHINCS+offers significant security against quantum attacks,its relatively slow computation times present a major obstacle to its practical deployment.To address this challenge,improving the computational efficiency of SPHINCS+becomes a critical task.The cryptographic operations in SPHINCS+rely on tweakable hash functions,with various hash algorithms available for selection.Among these,SHA-3 stands out as a widely adopted and NIST-standardized hash function,making it a preferred choice for implementation in SPHINCS+.In this work,we propose a dedicated coprocessor that integrates a SHA-3 accelerator along with its associated peripheral structure.This coprocessor is designed to extend the RISC-V instruction set by incorporating seven custom instructions,enabling efficient software-hardware co-acceleration.Furthermore,we investigate the parallelizable components within SPHINCS+,specifically the FORS and WOTS+Algorithms,to identify means for optimization.By leveraging thread-level parallelism through multi-core programming,we achieve significant improvements in performance.To validate the design,synthesis is performed using TSMC 28-nm CMOS technology at 800 MHz.Compared to the benchmark results from the ARM Cortex-M4 processor,our approach achieves an impressive 23.1×speedup in the overall single-core performance of SPHINCS+,with an additional 3.4×speedup for the verification process by utilizing multi-core acceleration.展开更多
基金Project supported by the Natural Science Foundation of Henan(Grant No.252300421304)the National Natural Science Foundation of China(Grant Nos.12204498,12474259+1 种基金12334011)the National Key Research and Development Program of China(Grant No.2022YFA1604302)。
文摘We propose a method to characterize the features of a cold strontium cloud in a magneto-optical trap(MOT)through the photoionization of cold Sr atoms in a custom-designed reaction microscope.Sr atoms in the dark state of 5s5p3P2 populated via the cascade transition 5s5p^(1)P_(1)→5s4d^(1)D_(2)→5s5p^(3)P_(2)accumulate a significant fraction,giving a long lifetime of 520 s.These atoms in the dark state are subsequently trapped by the gradient magnetic field of the MOT.By scanning the Sr+momentum distributions ionized with an 800 nm infrared femtosecond laser,we are able to outline the size of~0.55 mm in radius and the temperature of~0.40 mK for the dark-state atoms,which is significantly cooler than the MOT temperature of 3.3 mK trapped in the 461 nm.The size of MOT exhibits an oblate spheroidal distribution with a radius of approximately 0.35 mm and 0.55 mm,extracted with momenta of photoion and absorption imaging,respectively.The results using the photoion momenta are consistent with the expected results from absorption imaging,which confirms the method's reliability.The advantage of this method is the ability to simultaneously characterize the distribution information of atoms in different initial states within the cold atomic cloud.
基金supported by the National Natural Science Foundation of China under Grant 62234008Grant 61934002.
文摘SPHINCS+is a hash-based digital signature scheme that has been selected for post-quantum cryptography(PQC)standardization announced by the U.S.National Institute of Standards and Technology(NIST)in 2022.Although SPHINCS+offers significant security against quantum attacks,its relatively slow computation times present a major obstacle to its practical deployment.To address this challenge,improving the computational efficiency of SPHINCS+becomes a critical task.The cryptographic operations in SPHINCS+rely on tweakable hash functions,with various hash algorithms available for selection.Among these,SHA-3 stands out as a widely adopted and NIST-standardized hash function,making it a preferred choice for implementation in SPHINCS+.In this work,we propose a dedicated coprocessor that integrates a SHA-3 accelerator along with its associated peripheral structure.This coprocessor is designed to extend the RISC-V instruction set by incorporating seven custom instructions,enabling efficient software-hardware co-acceleration.Furthermore,we investigate the parallelizable components within SPHINCS+,specifically the FORS and WOTS+Algorithms,to identify means for optimization.By leveraging thread-level parallelism through multi-core programming,we achieve significant improvements in performance.To validate the design,synthesis is performed using TSMC 28-nm CMOS technology at 800 MHz.Compared to the benchmark results from the ARM Cortex-M4 processor,our approach achieves an impressive 23.1×speedup in the overall single-core performance of SPHINCS+,with an additional 3.4×speedup for the verification process by utilizing multi-core acceleration.
