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Multiparty Quantum Key Agreement Based on Three-Photon Entanglement with Unidirectional Qubit Transmission
摘要： A multiparty quantum key agreement protocol based on three-photon entangled states is proposed. In this scheme, the quantum channel between all parties is that of a closed loop, in which the qubit transmission is one-way. Each party can obtain the sum of the other parties’ secret key values through the coding rules instead of extracting their private keys. The shared secret key cannot be determined by any subset of all the participants except the universal set and each party makes an equal contribution to the final key. Moreover, the security analysis shows our protocol can resist both outside attacks and inside attacks.
关键词： Quantum cryptography,Three-photon entanglement,One-way qubit transmission,Quantum key agreement
更新于2025-09-23 15:23:52
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Influence of impurity on the rate of single photon superradiance and photon transport in disordered N qubit chain
摘要： We investigate the rate of superradiant emission for a number of artificial atoms (qubits) embedded in a one-dimensional open waveguide. More specifically, we study the 1D (N+1)- qubit chain where N qubits are identical with respect to their excitation frequency Ω but have different rates of spontaneous emission Γn, and a single impurity qubit which is different from N qubits by its excitation frequency ΩP and the rate of spontaneous emission ΓP . We performed exact diagonalization of Hamiltonian and showed that the system has two hybridized collective states one of which accumulates the widths of all qubits. The energy spectrum of these states and corresponding probabilities are investigated as a function of the frequency detuning between the impurity and other qubits in a chain. It is shown that the inclusion of the impurity qubit alters the resonance widths of the system if the total width overlaps the frequency detuning between qubits and the impurity. In this case the resonance widths experience a significant repulsion. The photon transmission through disordered N- qubit chain with the impurity qubit is also considered. It is shown that a single photon transport through this system is described by a simple expression which predicts for specific photon frequency the existence of a complete transmission peak and transparency window between frequencies Ω and ΩP .
关键词： superradiance,impurity,photon transport,qubit chain,non-Hermitian Hamiltonian
更新于2025-09-23 15:23:52
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The Investigation of WGM Effective Potential from Micro PANDA Ring Resonator
摘要： In this work, the whispering gallery mode effective potential generated by micro PANDA ring resonator for a two level system of atom–electric field coupling is investigated and presented. The depth of trapping potential is proportional to electric intensity and damping rate of transition of dipole polarization. The trial harmonics potential well is established by using dipole potential under ac Stark effect. The optimum intensity and lifetime for each WGM trapping wavelengths under the effect of thermal noise is reported.
关键词： optical tweezers,Trapping potential,atomic qubit
更新于2025-09-23 15:23:52
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Polygamy relation for the Rényi-$$\alpha $$α entanglement of assistance in multi-qubit systems
摘要： We prove a new polygamy relation of multi-party quantum entanglement in terms of Rényi-α entanglement of assistance for (√7?1)/2 ≤ α ≤ (√13?1)/2. This class of polygamy inequality reduces to the polygamy inequality based on entanglement of assistance since Rényi-α entanglement is a generalization of entanglement of formation.
关键词： Rényi-α entanglement of assistance,Multi-qubit systems,Polygamy relation
更新于2025-09-23 15:22:29
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QRCI: A new quantum representation model of color digital images
摘要： In this paper, a new quantum representation model of color digital images (QRCI) is investigated, in which the color information is encoded by the basis states of qubit sequences. QRCI model utilizes 2n+6 qubits to store a color digital image with size 2n×2n. Compared with the existing NCQI representation model, the storage capacity of QRCI improves 218 times. Moreover, some quantum color image processing operations concerning channels and bit-planes based on QRCI are discussed and their quantum circuits are designed. Comparison results of the quantum circuits indicate that these operations based on QRCI have lower quantum cost than NCQI. Therefore, the new proposed QRCI representation model can save more storage space and it is more convenient to conduct quantum color image processing operations concerning channels and bit-planes. This work will help the researchers to further investigate more complex quantum color image processing operations based on QRCI.
关键词： Quantum computation,Quantum cost,Quantum image representation model,Quantum color image processing,Storage capacity,Qubit
更新于2025-09-23 15:22:29
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Measurement-device-independent and arbitrarily loss-tolerant verification of quantum steering
摘要： We propose a method to verify quantum steering for two-qubit states with an arbitrary amount of null results when both the steering and steered parties cannot be trusted. We converted the steering inequality proposed in a recent article [Phys. Rev. X 2, 031003 (2012)] to a corresponding measurement-device-independent steering criterion that depends on the heralding efficiency of the steering party, number of measurement settings, and imperfection of the state preparation. As a result, for a relative frequency of valid measurement outcomes ηH, the steering can be verified using a number of different measurement settings larger than 1/ηH and maximally entangled states. Furthermore, steerability is guaranteed as long as the measurement efficiency of the steered party is nonzero. Our result is useful for loss-tolerant and measurement-device-independent steering tasks.
关键词： two-qubit states,loss-tolerant,quantum steering,measurement-device-independent,heralding efficiency
更新于2025-09-23 15:22:29
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Universal detection of entanglement in two-qubit states using only two copies
摘要： We revisit the problem of detection of entanglement of an unknown two-qubit state using minimal resources. Using weak values and just two copies of an arbitrary two-qubit state, we present a protocol where a postselection measurement in the computational basis provides enough information to identify if the state is entangled or not. Our protocol enables complete state identification with a single-setting postselection measurement on two copies of the state. It follows that by restricting to pure states, the global interaction required for determining the weak values can be realized by local operations. We further show that our protocol is robust against errors arising from inappropriate global interactions applied during weak value determination.
关键词： weak values,quantum information,two-qubit states,entanglement detection
更新于2025-09-23 15:22:29
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Deterministic Joint Remote State Preparation of an Arbitrary Equatorial Three-Qubit State
摘要： We propose a new scheme for joint remote preparation of an arbitrary equatorial three-qubit state by using three three-qubit GHZ states as the quantum channel. In our scheme, eight different projective measurement basis vectors are needed. It is shown that the successful probability of our scheme is 100% by performing the appropriate unitary operations.
关键词： GHZ state,Three-qubit state,Joint remote state preparation
更新于2025-09-23 15:22:29
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Nonadiabatic Geometric Quantum Computation with Parametrically Tunable Coupling
摘要： Nonadiabatic geometric quantum computation is promising as it is robust against certain types of local noises. However, its experimental implementation is challenging due to the need for complex control on multilevel and/or multiple quantum systems. Here, we propose to implement it on a two-dimensional square superconducting qubit lattice. In the construction of our geometric quantum gates, we only use the simplest and experimentally accessible control over the qubit states of the involved quantum systems, without introducing any auxiliary state. Specifically, our scheme is achieved by parametrically tunable all-resonant interaction, which leads to high-fidelity quantum gates. Meanwhile, this simple implementation can be conveniently generalized to a composite scenario, which can further suppress the systematic error during the gate operations. In addition, universal nonadiabatic geometric quantum gates in decoherence-free subspace can also be realized based on the tunable coupling between only two transmon qubits, without consulting multiple qubits and only using two physical qubits to encode a logical qubit. Therefore, our proposal provides a promising way to achieve high-fidelity geometric manipulation for robust solid-state quantum computation.
关键词： decoherence-free subspace,parametrically tunable coupling,Nonadiabatic geometric quantum computation,superconducting qubit lattice
更新于2025-09-23 15:21:21
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Charge qubit under optical control in a thin semiconductor slab
摘要： The dynamics of a single-electron double quantum dot (charge qubit) in an optical microcavity has been theoretically analysed taking into account the influence of optical and acoustic phonons. The Lamb modes of a two-dimensional mechanical resonator (thin slab) are considered as an example of an acoustic phonon subsystem. It is found that an optical phonon mode can be used as a qubit control tool, similar to the microcavity photon one. The probability of the quantum operation ‘NOT’ has been calculated for two qubit control scenarios: in the microcavity photon field and in the combined photon – phonon field of a microcavity and slab. It is shown that the coherent energy exchange between a qubit and a set of acoustic phonon modes reduces this probability, which depends on the number of modes, the initial state of the phonon field, and the decay rate of modes.
关键词： acoustic phonons,quantum dot,microcavity,quantum computer,qubit
更新于2025-09-23 15:21:21