We present a method to implement the quantum partial search of the database separated into any number of blocks with qudits, D-level quantum systems. Compared with the partial search using qubits, our method needs few...We present a method to implement the quantum partial search of the database separated into any number of blocks with qudits, D-level quantum systems. Compared with the partial search using qubits, our method needs fewer iteration steps and uses the carriers of the information more economically. To illustrate how to realize the idea with concrete physical systems, we propose a scheme to carry out a twelve-dimensional partial search of the database partitioned into three blocks with superconducting quantum interference devices （SQUIDs） in cavity QED. Through the appropriate modulation of the amplitudes of the microwave pulses, the scheme can overcome the non-identity of the cavity-SQUID coupling strengths due to the parameter variations resulting from the fabrication processes. Numerical simulation under the influence of the cavity and SQUID decays shows that the scheme could be achieved efficiently within current state-of-the-art technology.展开更多
Quantum circuit model has been widely explored for various quantum applications such as Shors algorithm and Grovers searching algorithm.Most of previous algorithms are based on the qubit systems.Herein a proposal for ...Quantum circuit model has been widely explored for various quantum applications such as Shors algorithm and Grovers searching algorithm.Most of previous algorithms are based on the qubit systems.Herein a proposal for a universal circuit is given based on the qudit system,which is larger and can store more information.In order to prove its universality for quantum applications,an explicit set of one-qudit and two-qudit gates is provided for the universal qudit computation.The one-qudit gates are general rotation for each two-dimensional subspace while the two-qudit gates are their controlled extensions.In comparison to previous quantum qudit logical gates,each primitive qudit gate is only dependent on two free parameters and may be easily implemented.In experimental implementation,multilevel ions with the linear ion trap model are used to build the qudit systems and use the coupling of neighbored levels for qudit gates.The controlled qudit gates may be realized with the interactions of internal and external coordinates of the ion.展开更多
The quantum Fourier transform and quantum phase estimation are the key components for many quantum algorithms, such as order-finding, factoring, and etc. In this article, the general procedure of quantum Fourier trans...The quantum Fourier transform and quantum phase estimation are the key components for many quantum algorithms, such as order-finding, factoring, and etc. In this article, the general procedure of quantum Fourier transform and phase estimation are investigated for high dimensional case run in a qudit quantum computer, and the quantum circuits are They can be seen as subroutines in a main program given.展开更多
Single-photon entanglement(SPE) is an important source in quantum communication. In this paper, we put forward a single-photon-assisted noiseless linear amplification protocol to protect the SPE of an arbitrary polari...Single-photon entanglement(SPE) is an important source in quantum communication. In this paper, we put forward a single-photon-assisted noiseless linear amplification protocol to protect the SPE of an arbitrary polarization–time-bin qudit from the photon transmission loss caused by the practical channel noise. After the amplification, the fidelity of the SPE can be effectively increased. Meanwhile, the encoded polarization–time-bin features of the qudit can be well preserved. The protocol can be realized under the current experimental conditions. Moreover, the amplification protocol can be extended to resist complete photon loss and partial photon loss during the photon transmission. After the amplification, we can not only increase the fidelity of the target state, but also solve the decoherence problem simultaneously. Based on the above features, our amplification protocol may be useful in future quantum communication.展开更多
We propose a scheme for realizing a controlled teleportation of random M-qudit quantum information under the control of N agents. The resource consumption includes a prearranged （2M ＋ N ＋ 1）-qudit entangled quantu...We propose a scheme for realizing a controlled teleportation of random M-qudit quantum information under the control of N agents. The resource consumption includes a prearranged （2M ＋ N ＋ 1）-qudit entangled quantum channel and （2M ＋ N ＋1） log2 d-bit classical communication. And the quantum operations used in the teleportation process are a series of generalized Bell-state measurements, single-qudit measurements, qudit H-gates, qudit-Pauli gates and qudit phase gates. It is shown that the original state can be restored by the receiver only on condition that all the agents work in collaboration with each others. If one agent does not cooperate with the other, the original state cannot be fully recovered.展开更多
We present a systematic simple method to implement a generalized quantum control-NOT （CNOT） gate on two d-dimensional distributed systems. First, we show how the nonlocal generalized quantum CNOT gate can be impleme...We present a systematic simple method to implement a generalized quantum control-NOT （CNOT） gate on two d-dimensional distributed systems. First, we show how the nonlocal generalized quantum CNOT gate can be implemented with unity fidelity and unity probability by using a maximally entangled pair of qudits as a quantum channel. We also put forward a scheme for probabilistically implementing the nonlocal operation with unity fidelity by employing a partially entangled qudit pair as a quantum channel. Analysis of the scheme indicates that the use of partially entangled quantum channel for implementing the nonlocal generalized quantum CNOT gate leads to the problem of ＇the general optimal information extraction＇. We also point out that the nonlocal generalized quantum CNOT gate can be used in the entanglement swapping between particles belonging to distant users in a communication network and distributed quantum computer.展开更多
We present a scheme for quantum state sharing of an arbitrary qudit state by using nonmaximally entangled generalized Greenberger-Horne-Zeilinger （GHZ） states as the quantum channel and generalized Bell-basis states...We present a scheme for quantum state sharing of an arbitrary qudit state by using nonmaximally entangled generalized Greenberger-Horne-Zeilinger （GHZ） states as the quantum channel and generalized Bell-basis states as the joint measurement basis. We show that the probability of successful sharing an unknown qudit state depends on the joint measurements chosen by Alice. We also give an expression for the maximally probability of this scheme.展开更多
The utilization of qudits in quantum systems has led to significant advantages in quantum computation and information processing.Therefore,qudits have gained increased attention in recent research for their precise an...The utilization of qudits in quantum systems has led to significant advantages in quantum computation and information processing.Therefore,qudits have gained increased attention in recent research for their precise and efficient operations.In this work,we demonstrate the complete population transfer between the next-adjacent energy levels of a transmon qudit using the Pythagorean coupling method and energy level mapping.We achieve a|0>to|2>transfer with a process fidelity of 97.76%in the subspace spanned by|0>to|2>.Moreover,the transfer operation is achieved within a remarkably fast timescale,as short as 20 ns.This study may present a promising avenue for enhancing the operation flexibility and efficiency of qudits in future implementations.展开更多
Qudits have proven to be a powerful resource for quantum information processing,offering enhanced channel capacities,improved robustness to noise,and highly efficient implementations of quantum algorithms.The encoding...Qudits have proven to be a powerful resource for quantum information processing,offering enhanced channel capacities,improved robustness to noise,and highly efficient implementations of quantum algorithms.The encoding of photonic qudits in transverse-spatial degrees of freedom has emerged as a versatile tool for quantum information processing,allowing access to a vast information capacity within a single photon.We examine recent advances in quantum optical circuits with spatially structured light,focusing particularly on top-down approaches that employ complex mode-mixing transformations in free space and fibers.We highlight circuits based on platforms such as multi-plane light conversion,complex scattering media,multi-mode,and multi-core fibers.We discuss their applications for the manipulation and measurement of multi-dimensional and multi-mode quantum states.Furthermore,we discuss how these circuits have been employed to perform multi-party operations and multi-outcome measurements,thereby opening new avenues for scalable photonic quantum information processing.展开更多
Magnetic molecules have been proposed as scaffolds for novel quantum technologies,ranging from quantum sensing and quantum memory to multilevel quantum bits(qudits)and fault-tolerant quantum computation.Integration of...Magnetic molecules have been proposed as scaffolds for novel quantum technologies,ranging from quantum sensing and quantum memory to multilevel quantum bits(qudits)and fault-tolerant quantum computation.Integration of magnetic molecules into cutting-edge applications hinges on a deep understanding and tunability of their spin states.To date,the strategic manipulation of the local environment of the ion and careful selection of the magnetic core have enabled the desired tunability and scalability of the spin states.For such goals,however,extracting the anisotropic parameters that dictate the characteristics of the Spin Hamiltonian is challenging,especially for molecules consisting of multiple magnetic cores.We address these challenges by studying two cobalt(II)dinuclear systems,complicated by inherent spin–orbit coupling.We explore the magnetic properties of these systems in two temperature regimes:(i)at sub-Kelvin temperatures employing single crystals at 30 mK using a uniqueμSQUID-EPR technique that examines the microwave absorption peaks in the magnetisation data and their variation with field angle and frequency;and(ii)in bulk employing convectional SQUID magnetometry above 2 K i.e.,χMT(T)and M(H).Unexpectedly,sub-Kelvin temperature investigations reveal a negligible interaction,whereas the SQUID data reveal a much stronger interaction between the Co(II)ions.An understanding of these data is developed based on a strong coupling model and the coupling of two moieties with a spin-effective ground state.展开更多
The recently observed two-photon Landau-Zener-Stückelberg-Majorana(LZSM)effect in superconducting circuits[Phys.Rev.Lett.134060602(2025)]has provided a robust pathway for high-fidelity population transfer in qudi...The recently observed two-photon Landau-Zener-Stückelberg-Majorana(LZSM)effect in superconducting circuits[Phys.Rev.Lett.134060602(2025)]has provided a robust pathway for high-fidelity population transfer in qudit systems,but its adiabatic nature necessitates long operation times,which are vulnerable to decoherence.展开更多
Spin active molecules have been proposed for quantum computing,due to their unique advantages such as the possibility of having multiple eigenstates.Using pulse electron paramagnetic resonance,a Gd(Ⅲ)complex was thor...Spin active molecules have been proposed for quantum computing,due to their unique advantages such as the possibility of having multiple eigenstates.Using pulse electron paramagnetic resonance,a Gd(Ⅲ)complex was thoroughly investigated to demonstrate the protocol of harnessing the large spin quantum number of the rare-earth molecule and implementing a qudit.The desired anisotropy of the S=7/2 system,which makes all spin transitions addressable with an X-band spectrometer,was quantitatively determined at 10 K with a set of crystalfield parameters.The relatively long phase memory time,ca.1μs,of the oxygen-coordinated 4f spin was extended up to 16.8μs using dynamic decoupling pulse sequences.An arbitrary superposition state between each adjacent level pair was achieved by Rabi cycles with a crystal sample positioned in both perpendicular and parallel directions.Finally,a more detailed orientation mapping of the Rabi frequencies,which govern the quantum phase gate operation time,was provided based on the spin Hamiltonian.展开更多
Quantum information processing depends on the construction of a quantum bit(qubit).In particular,the intrinsic multilevel structures of 4f rare-earth complexes with high spin are suitable carriers for realizing high s...Quantum information processing depends on the construction of a quantum bit(qubit).In particular,the intrinsic multilevel structures of 4f rare-earth complexes with high spin are suitable carriers for realizing high scalability in the molecule-based highdimensional spin qubit.A single crystal of Gd(III)complex[Gd_(0.02)Y_(1.98)(pydc)6(H_(2)pip)_(3)]·20 H_(2)O(S=7/2)with 3-fold axial symmetry(C_(3))was characterized by the X-band electron paramagnetic resonance in different orientations to resolve the energy-level structures,research the spin dynamic properties,and verify the ability to realize arbitrary quantum manipulation.The Rabi frequencies in two specific orientations,(C_(3)∥B_(0)and C_(3)⊥B_(0)),were wellmatched with the diverse Rabi cycle model,indicating that the selective transitions in the single crystal samples could be accurately predicted in any direction along the static magnetic field B_(0).展开更多
Two different schemes are presented for quantum teleportation of an arbitrary two-qudit state using a non-maximally four-qudit cluster state as the quantum channel. The first scheme is based on the Bell-basis measurem...Two different schemes are presented for quantum teleportation of an arbitrary two-qudit state using a non-maximally four-qudit cluster state as the quantum channel. The first scheme is based on the Bell-basis measurements and the re-ceiver may probabilistically reconstruct the original state by performing proper transformation on her particles and an auxiliary two-level particle; the second scheme is based on the generalized Bell-basis measurements and the probability of successfully teleporting the unknown state depends on those measurements which are adjusted by Alice. A comparison of the two schemes shows that the latter has a smaller probability than that of the former and contrary to the former, the channel information and auxiliary qubit are not necessary for the receiver in the latter.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.10774192)
文摘We present a method to implement the quantum partial search of the database separated into any number of blocks with qudits, D-level quantum systems. Compared with the partial search using qubits, our method needs fewer iteration steps and uses the carriers of the information more economically. To illustrate how to realize the idea with concrete physical systems, we propose a scheme to carry out a twelve-dimensional partial search of the database partitioned into three blocks with superconducting quantum interference devices （SQUIDs） in cavity QED. Through the appropriate modulation of the amplitudes of the microwave pulses, the scheme can overcome the non-identity of the cavity-SQUID coupling strengths due to the parameter variations resulting from the fabrication processes. Numerical simulation under the influence of the cavity and SQUID decays shows that the scheme could be achieved efficiently within current state-of-the-art technology.
基金supported by the National Natural Science Foundation of China(Grant Nos.61303039 and 11226336)the Fundamental Research Funds for the Central Universities(Grant No.2682014CX095)the Science Foundation Ireland(SFI)under the International Strategic CooperationAward Grant Number SFI/13/ISCA/2845
文摘Quantum circuit model has been widely explored for various quantum applications such as Shors algorithm and Grovers searching algorithm.Most of previous algorithms are based on the qubit systems.Herein a proposal for a universal circuit is given based on the qudit system,which is larger and can store more information.In order to prove its universality for quantum applications,an explicit set of one-qudit and two-qudit gates is provided for the universal qudit computation.The one-qudit gates are general rotation for each two-dimensional subspace while the two-qudit gates are their controlled extensions.In comparison to previous quantum qudit logical gates,each primitive qudit gate is only dependent on two free parameters and may be easily implemented.In experimental implementation,multilevel ions with the linear ion trap model are used to build the qudit systems and use the coupling of neighbored levels for qudit gates.The controlled qudit gates may be realized with the interactions of internal and external coordinates of the ion.
基金Supported by the National Natural Science Foundation of China Grant No.10874098the National Basic Research Program of China under Grant Nos.2009CB929402 and 2011CB9216002
文摘The quantum Fourier transform and quantum phase estimation are the key components for many quantum algorithms, such as order-finding, factoring, and etc. In this article, the general procedure of quantum Fourier transform and phase estimation are investigated for high dimensional case run in a qudit quantum computer, and the quantum circuits are They can be seen as subroutines in a main program given.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11474168 and 11747161)the Priority Academic Program Development of Jiangsu Higher Education Institutions,Chinathe China Postdoctoral Science Foundation(Grant No.2018M642293)
文摘Single-photon entanglement(SPE) is an important source in quantum communication. In this paper, we put forward a single-photon-assisted noiseless linear amplification protocol to protect the SPE of an arbitrary polarization–time-bin qudit from the photon transmission loss caused by the practical channel noise. After the amplification, the fidelity of the SPE can be effectively increased. Meanwhile, the encoded polarization–time-bin features of the qudit can be well preserved. The protocol can be realized under the current experimental conditions. Moreover, the amplification protocol can be extended to resist complete photon loss and partial photon loss during the photon transmission. After the amplification, we can not only increase the fidelity of the target state, but also solve the decoherence problem simultaneously. Based on the above features, our amplification protocol may be useful in future quantum communication.
基金Project supported by the Scientific Research Fund of Hunan Provincial Education Bureau （Grant No 05B041）, the Foundation for Key Program of Ministry of Education, China （Grant No 206103）, the Science Foundation for Post Doctorate Research from the Ministry of Science and Technology of China （Grant No 2005037695）, and the Natural Science Foundation of Hunan Province . （Grant Nos 04JJ3017 and 05JJ30012）.
文摘We propose a scheme for realizing a controlled teleportation of random M-qudit quantum information under the control of N agents. The resource consumption includes a prearranged （2M ＋ N ＋ 1）-qudit entangled quantum channel and （2M ＋ N ＋1） log2 d-bit classical communication. And the quantum operations used in the teleportation process are a series of generalized Bell-state measurements, single-qudit measurements, qudit H-gates, qudit-Pauli gates and qudit phase gates. It is shown that the original state can be restored by the receiver only on condition that all the agents work in collaboration with each others. If one agent does not cooperate with the other, the original state cannot be fully recovered.
文摘We present a systematic simple method to implement a generalized quantum control-NOT （CNOT） gate on two d-dimensional distributed systems. First, we show how the nonlocal generalized quantum CNOT gate can be implemented with unity fidelity and unity probability by using a maximally entangled pair of qudits as a quantum channel. We also put forward a scheme for probabilistically implementing the nonlocal operation with unity fidelity by employing a partially entangled qudit pair as a quantum channel. Analysis of the scheme indicates that the use of partially entangled quantum channel for implementing the nonlocal generalized quantum CNOT gate leads to the problem of ＇the general optimal information extraction＇. We also point out that the nonlocal generalized quantum CNOT gate can be used in the entanglement swapping between particles belonging to distant users in a communication network and distributed quantum computer.
文摘We present a scheme for quantum state sharing of an arbitrary qudit state by using nonmaximally entangled generalized Greenberger-Horne-Zeilinger （GHZ） states as the quantum channel and generalized Bell-basis states as the joint measurement basis. We show that the probability of successful sharing an unknown qudit state depends on the joint measurements chosen by Alice. We also give an expression for the maximally probability of this scheme.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.11890704,12004042,12104055,and 12104056)Natural Science Foundation of Beijing (Grant No.Z190012)Key Area Research and Development Program of Guangdong Province (Grant No.2018B030326001)。
文摘The utilization of qudits in quantum systems has led to significant advantages in quantum computation and information processing.Therefore,qudits have gained increased attention in recent research for their precise and efficient operations.In this work,we demonstrate the complete population transfer between the next-adjacent energy levels of a transmon qudit using the Pythagorean coupling method and energy level mapping.We achieve a|0>to|2>transfer with a process fidelity of 97.76%in the subspace spanned by|0>to|2>.Moreover,the transfer operation is achieved within a remarkably fast timescale,as short as 20 ns.This study may present a promising avenue for enhancing the operation flexibility and efficiency of qudits in future implementations.
基金financial support from the European Research Council(ERC)Starting Grant PIQUaNT(Grant No.950402)the UK Engineering and Physical Sciences Research Council(EPSRC)(Grant Nos.EP/Z533208/1 and EP/W003252/1)the Royal Academy of Engineering Chair in Emerging Technologies programme(Grant No.CiET-2223-112)。
文摘Qudits have proven to be a powerful resource for quantum information processing,offering enhanced channel capacities,improved robustness to noise,and highly efficient implementations of quantum algorithms.The encoding of photonic qudits in transverse-spatial degrees of freedom has emerged as a versatile tool for quantum information processing,allowing access to a vast information capacity within a single photon.We examine recent advances in quantum optical circuits with spatially structured light,focusing particularly on top-down approaches that employ complex mode-mixing transformations in free space and fibers.We highlight circuits based on platforms such as multi-plane light conversion,complex scattering media,multi-mode,and multi-core fibers.We discuss their applications for the manipulation and measurement of multi-dimensional and multi-mode quantum states.Furthermore,we discuss how these circuits have been employed to perform multi-party operations and multi-outcome measurements,thereby opening new avenues for scalable photonic quantum information processing.
基金the DFG-CCR 1573“4f for future”(project B4)and the Karlsruhe Nano Micro Facility(KNMF,https://www.kit.edu/knmf)for the provision of access to instruments at their laboratoriesthe Alexander von Humboldt Fellowship for experienced researchers for supportthe German Research Foundation(DFG)for the Gottfried Wilhelm Leibniz-Award,ZVN-2020_WE 4458-5。
文摘Magnetic molecules have been proposed as scaffolds for novel quantum technologies,ranging from quantum sensing and quantum memory to multilevel quantum bits(qudits)and fault-tolerant quantum computation.Integration of magnetic molecules into cutting-edge applications hinges on a deep understanding and tunability of their spin states.To date,the strategic manipulation of the local environment of the ion and careful selection of the magnetic core have enabled the desired tunability and scalability of the spin states.For such goals,however,extracting the anisotropic parameters that dictate the characteristics of the Spin Hamiltonian is challenging,especially for molecules consisting of multiple magnetic cores.We address these challenges by studying two cobalt(II)dinuclear systems,complicated by inherent spin–orbit coupling.We explore the magnetic properties of these systems in two temperature regimes:(i)at sub-Kelvin temperatures employing single crystals at 30 mK using a uniqueμSQUID-EPR technique that examines the microwave absorption peaks in the magnetisation data and their variation with field angle and frequency;and(ii)in bulk employing convectional SQUID magnetometry above 2 K i.e.,χMT(T)and M(H).Unexpectedly,sub-Kelvin temperature investigations reveal a negligible interaction,whereas the SQUID data reveal a much stronger interaction between the Co(II)ions.An understanding of these data is developed based on a strong coupling model and the coupling of two moieties with a spin-effective ground state.
基金supported by the National Natural Science Foundation of China(Grant Nos.12575032,62571494,12304407,and 12274376)the Natural Science Foundation of Henan Province(Grant No.232300421075)the China Postdoctoral Science Foundation(Grant Nos.2023TQ0310 and 2024M762973)。
文摘The recently observed two-photon Landau-Zener-Stückelberg-Majorana(LZSM)effect in superconducting circuits[Phys.Rev.Lett.134060602(2025)]has provided a robust pathway for high-fidelity population transfer in qudit systems,but its adiabatic nature necessitates long operation times,which are vulnerable to decoherence.
基金supported by the National Basic Research Program of China(2017YFA0204903 and 2018YFA0306003)National Natural Science Foundation of China(21822301 and 51802346)Beijing Academy of Quantum Information Sciences(Y18G23).
文摘Spin active molecules have been proposed for quantum computing,due to their unique advantages such as the possibility of having multiple eigenstates.Using pulse electron paramagnetic resonance,a Gd(Ⅲ)complex was thoroughly investigated to demonstrate the protocol of harnessing the large spin quantum number of the rare-earth molecule and implementing a qudit.The desired anisotropy of the S=7/2 system,which makes all spin transitions addressable with an X-band spectrometer,was quantitatively determined at 10 K with a set of crystalfield parameters.The relatively long phase memory time,ca.1μs,of the oxygen-coordinated 4f spin was extended up to 16.8μs using dynamic decoupling pulse sequences.An arbitrary superposition state between each adjacent level pair was achieved by Rabi cycles with a crystal sample positioned in both perpendicular and parallel directions.Finally,a more detailed orientation mapping of the Rabi frequencies,which govern the quantum phase gate operation time,was provided based on the spin Hamiltonian.
基金supported by the Natural Science Foundation of China(grant nos.22271311,22325503,22250001,U20A6002,and 222203033)the Fundamental Research Funds for the Central Universities(2023ZYGXZR002)+2 种基金the Guangdong Provincial Quantum Science Strategic Initiative(GDZX2301002)Natural Science Foundation of Hunan Province of China(grant no.2023JJ20049)the National University of Defense Technology,China(grant no.23-ZZCX-ZZGC-01-15).
文摘Quantum information processing depends on the construction of a quantum bit(qubit).In particular,the intrinsic multilevel structures of 4f rare-earth complexes with high spin are suitable carriers for realizing high scalability in the molecule-based highdimensional spin qubit.A single crystal of Gd(III)complex[Gd_(0.02)Y_(1.98)(pydc)6(H_(2)pip)_(3)]·20 H_(2)O(S=7/2)with 3-fold axial symmetry(C_(3))was characterized by the X-band electron paramagnetic resonance in different orientations to resolve the energy-level structures,research the spin dynamic properties,and verify the ability to realize arbitrary quantum manipulation.The Rabi frequencies in two specific orientations,(C_(3)∥B_(0)and C_(3)⊥B_(0)),were wellmatched with the diverse Rabi cycle model,indicating that the selective transitions in the single crystal samples could be accurately predicted in any direction along the static magnetic field B_(0).
基金Supported by the Natural Science Research Project of Shanxi Province (Grant No. 2004A15)
文摘Two different schemes are presented for quantum teleportation of an arbitrary two-qudit state using a non-maximally four-qudit cluster state as the quantum channel. The first scheme is based on the Bell-basis measurements and the re-ceiver may probabilistically reconstruct the original state by performing proper transformation on her particles and an auxiliary two-level particle; the second scheme is based on the generalized Bell-basis measurements and the probability of successfully teleporting the unknown state depends on those measurements which are adjusted by Alice. A comparison of the two schemes shows that the latter has a smaller probability than that of the former and contrary to the former, the channel information and auxiliary qubit are not necessary for the receiver in the latter.
