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[IEEE 2018 IEEE 7th Data Driven Control and Learning Systems Conference (DDCLS) - Enshi (2018.5.25-2018.5.27)] 2018 IEEE 7th Data Driven Control and Learning Systems Conference (DDCLS) - Quantum Noise Protection via Weak Measurement for Quantum Mixed States
摘要： Due to the interaction with the environment, a quantum state is often affected by the different types of noises which becomes to one of the biggest problems for practical quantum computation. We study the possibility of protecting the mixed state of a quantum system that goes through noise by weak measurements and control operations. The aim is to find the optimal measurement strength and control operations and make the input and output states as close as possible. We show that our scheme can effectively protect arbitrary mixed states against typical types of noise sources: amplitude damping, phase damping and amplitude-phase damping. The optimal measurement and control operators are deduced in different bases of the Bloch sphere to find the best control scheme for each type of noise. The effectiveness of our control scheme is demonstrated by simulation results.
关键词： quantum system control,Open quantum system,optimal noise protection,weak measurement
更新于2025-09-23 15:23:52
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Quantum error correction using weak measurements
摘要： The standard quantum error correction protocols use projective measurements to extract the error syndromes from the encoded states. We consider the more general scenario of weak measurements, where only partial information about the error syndrome can be extracted from the encoded state. We construct a feedback protocol that probabilistically corrects the error based on the extracted information. Using numerical simulations of one-qubit error correction codes, we show that our error correction succeeds for a range of the weak measurement strength, where (a) the error rate is below the threshold beyond which multiple errors dominate, and (b) the error rate is less than the rate at which weak measurement extracts information. We observe that error correction based on projective measurements is always superior to that based on weak measurements; so the latter is worthwhile only if the former is unavailable due to some reason, and error correction with too small a measurement strength should be avoided.
关键词： Projective measurement,Quantum error correction,Weak measurement,Quantum trajectory
更新于2025-09-23 15:22:29
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Optimized decoherence suppression of tripartite entanglement in finite temperature environments using weak measurement and quantum measurement reversal
摘要： In practical application, since quantum entanglement is inevitably destroyed by thermal noise resulted from environment, protecting entanglement from decoherence in thermal bath environment becomes a critically important issue in the field of quantum information. In this work, we propose a scheme to protect the tripartite Greenberger–Horne–Zeilinger (GHZ) entanglement state subjected to the generalized amplitude damping (GAD) channel based on the quantum technique of weak measurement (WM) and quantum measurement reversal (QMR). By optimizing the strengths of WM and QMR, the decoherence caused by the channel can be effectively suppressed. The results show that after performing the optimal pre- and post-channel weak measurement, the negativity of the GHZ state can be effectively improved with a certain probability, and the phenomenon of sudden death can be delayed to a certain degree. This scheme can be applied to the decoherence suppression of GAD channel at finite temperature.
关键词： generalized amplitude damping channel,weak measurement,Decoherence suppression,tripartite entanglement.
更新于2025-09-23 15:22:29
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Determining complementary properties using weak-measurement: uncertainty, predictability, and disturbance
摘要： It is often said that measuring a system’s position must disturb the complementary property, momentum, by some minimum amount due to the Heisenberg uncertainty principle. Using a “weak-measurement”, this disturbance can be reduced. One might expect this comes at the cost of also reducing the measurement’s precision. However, it was recently demonstrated that a sequence consisting of a weak position measurement followed by a regular momentum measurement can probe a quantum system at a single point, with zero width, in position-momentum space. Here, we study this “joint weak-measurement” and reconcile its compatibility with the uncertainty principle. While a single trial probes the system with a resolution that can saturate Heisenberg’s limit, we show that averaging over many trials can be used to surpass this limit. The weak-measurement does not trade-away precision, but rather another type of uncertainty called “predictability” which quantifies the certainty of retrodicting the measurement’s outcome.
关键词： weak-measurement,Heisenberg uncertainty principle,phase space,predictability,quantum measurement
更新于2025-09-23 15:21:01
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Enhance quantum teleportation under correlated amplitude damping decoherence by weak measurement and quantum measurement reversal
摘要： A scheme which aims to protect the quantum teleportation from correlated amplitude damping decoherence is proposed. Comparing with the results of uncorrelated amplitude damping noise, we ?nd that the correlated effects enable to improve the ?delity with the given decoherence parameter. Moreover, we show that the combination of weak measurement and quantum measurement reversal could drastically enhance the ?delity in both uncorrelated and correlated amplitude damping noise. Our results extend the ability of weak measurement as a technique in various quantum information processes which are affected by correlated noise.
关键词： Weak measurement,Correlated amplitude damping channel,Quantum teleportation
更新于2025-09-10 09:29:36
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Quantum Zeno effect and the many-body entanglement transition
摘要： We introduce and explore a one-dimensional “hybrid” quantum circuit model consisting of both unitary gates and projective measurements. While the unitary gates are drawn from a random distribution and act uniformly in the circuit, the measurements are made at random positions and times throughout the system. By varying the measurement rate we can tune between the volume law entangled phase for the random unitary circuit model (no measurements) and a “quantum Zeno phase” where strong measurements suppress the entanglement growth to saturate in an area law. Extensive numerical simulations of the quantum trajectories of the many-particle wave functions (exploiting Clifford circuitry to access systems up to 512 qubits) provide evidence for a stable “weak measurement phase” that exhibits volume-law entanglement entropy, with a coef?cient decreasing with increasing measurement rate. We also present evidence for a continuous quantum dynamical phase transition between the “weak measurement phase” and the “quantum Zeno phase,” driven by a competition between the entangling tendencies of unitary evolution and the disentangling tendencies of projective measurements. Detailed steady-state and dynamic critical properties of this quantum entanglement transition are accessed.
关键词： quantum circuit model,volume law entangled phase,projective measurements,weak measurement phase,quantum Zeno effect,many-body entanglement transition,area law,quantum dynamical phase transition
更新于2025-09-09 09:28:46
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Rapid Separation of Enantiomeric Impurities in Chiral Molecules by a Self-Referential Weak Measurement System
摘要： We propose a self-referential fast detection scheme for a frequency domain weak measurement system for the detection of enantiomeric impurities in chiral molecules. In a transmissive weak measurement system, the optical rotation (OR) is used to modify the pre-selected polarization state and the post-selection polarization state. We obtained the sum and difference of the optical rotations produced by the sample and the standard by rotating the quarter wave plate in the system. Then, we estimate the ratio of chiral molecules to enantiomeric impurities using the ratio of the central wavelength shifts caused by the addition and subtraction states described above. In this paper, our system has an optical resolution of 1.88 × 10?5?. At the same time, we completed the detection of the ratio of the two substances in the mixture of L-proline and D-proline in different proportions, which proved that our system can quickly detect the content of enantiomeric impurities in chiral molecules.
关键词： enantiomeric impurity content detection,common light path system,weak measurement,self-reference
更新于2025-09-09 09:28:46
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Weak measurement and weak values — New insights and effects in reflectivity and scattering processes
摘要： Recently, the notions of Weak Measurement (WM), Weak Value (WV) and Two-State-Vector Formalism (TSVF), firstly introduced by Aharonov and collaborators, have extended the theoretical frame of standard quantum mechanics, thus providing a quantum-theoretical formalism for extracting new information from a system in the limit of small disturbance to its state. Here we provide an application to the case of two-body scattering with one body weakly interacting with its environment — e.g. a neutron being scattered from a H2 molecule physisorbed in a carbon nanotube. In particular, we make contact with the field of incoherent inelastic neutron scattering from condensed systems. We provide a physically compelling prediction of a new quantum effect — a momentum transfer deficit; or equivalently, an enhanced energy transfer; or an apparent reduction of the mass of the struck particle. E.g., when a neutron collides with a H2 molecule in a C-nanotube and excites its translational motion along the nanotube, it apparently exchanges energy and momentum with a fictitious particle with mass of 0.64 atomic mass units. Experimental results are shown and discussed in the new theoretical frame. The effect under consideration has no conventional interpretation, thus also supporting the novelty of the quantum theoretical framework of WV and TVSF. Some speculative remarks about possible applications being of technological interest (fuel cells and hydrogen storage; Li+ batteries; information and communication technology) are shortly mentioned.
关键词： energy transfer,mass reduction,neutron scattering,momentum transfer deficit,Two-State-Vector Formalism,Weak Value,Weak Measurement
更新于2025-09-04 15:30:14
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-Point Splitting
摘要： We investigate points of circular polarization in the far field of elliptically polarized dipoles and establish a relation between the angular position and helicity of these C points and the dipole moment. In the case of highly eccentric dipoles, the C points of opposite handedness exhibit only a small angular separation and occur in the low intensity region of the emission pattern. In this regard, we introduce an optical weak measurement approach that utilizes the transverse electric (azimuthal) and transverse magnetic (radial) far-field polarization basis. Projecting the far field onto a spatially varying postselected polarization state reveals the angular separation and the helicity of the C points. We demonstrate the applicability of this approach and determine the elliptical dipole moment of a particle sitting on an interface by measuring the C points in its far field.
关键词： C points,dipole moment,far field,circular polarization,weak measurement
更新于2025-09-04 15:30:14
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Exploration of entropic uncertainty relation for two accelerating atoms immersed in a bath of electromagnetic field
摘要： The uncertainty principle as an elementary theory of quantum mechanics plays an important role in quantum information science. In this paper, we study the dynamics of quantum-memory-assisted entropic uncertainty relation for two accelerating atoms coupled with a bath of fluctuating electromagnetic field. The master equation that the system evolution obeys is firstly derived. We find that the mixedness is bound up with the entropic uncertainty. For equilibrium state, the tightness of uncertainty vanishes. For the initial maximum entangled state, the tightness of uncertainty experiences a slight increase and then declines to zero with evolution time. It is found that the greater acceleration makes the uncertainty faster reach a maximum value and stable value. For a fixed acceleration, the uncertainty with different two-atom separations converges to a fixed value. Furthermore, we utilize weak measurement reversal to manipulate the entropic uncertainty. Our explorations may suggest a method of probing entanglement, acceleration effect and vacuum fluctuation effect with entropic uncertainty.
关键词： Fluctuating electromagnetic field,Weak measurement reversal,Dynamics,Mixedness,Entropic uncertainty
更新于2025-09-04 15:30:14