arXiv subjects

Ying-Jie Zhang

Publications and source records attributed to Ying-Jie Zhang.

At least 19 recordsLinked to original sources

arXiv2026

Expanding the trilayer Ruddlesden-Popper nickelate family: Synthesis and characterization of Sm$_4$Ni$_3$O$_{10-δ}$ single crystals

The discovery of high-temperature superconductivity in Ruddlesden-Popper (RP) nickelates has attracted significant attention. Bulk superconductivity emerges under pressure in trilayer nickelates La$_4$Ni$_3$O$_{10-δ}$ (T$_c$ $\approx$ 30 K) and Pr$_4$Ni$_3$O$_{10-δ}$ (T$_c$ $\approx$ 40.5 K), where the reduced ionic radius of Pr$^{3+}$ may generate internal chemical pressure and enhance T$_c$. However, synthesizing trilayer RP phases with smaller rare-earth elements (Ln) is extremely challenging. So far, only the La, Pr, and Nd analogues have been synthesized with stable phases in the single rare-earth form. Here we report the first successful high-pressure and high-temperature (HPHT) synthesis of samarium-based compound Sm$_4$Ni$_3$O$_{10-δ}$. Magnetization and transport measurements consistently confirm a density wave (DW) transition at ~180 K at ambient pressure. Through a careful fitting to the structural data of Sm$_4$Ni$_3$O$_{10-δ}$, it is found that the bond angle of (Ni-O-Ni) associating with the interlayer apical oxygen is much smaller than 180$^{\circ}$, which was assumed to be the key factor for the occurrence of superconductivity. By applying pressures up to 80 GPa, despite partial suppression of insulating behavior and the DW order, but superconductivity is not observed in our present study. Density functional theory calculations suggest that the 3d$_{z^2}$ and 3d$_{x^2-y^2}$ are separated from other t$_{2g}$ orbitals and make a primary contribution to the Fermi surface. The newly synthesized trilayer nickelate Sm$_4$Ni$_3$O$_{10-δ}$ offers a unique platform for probing the fundamental physics of RP nickelates.

cond-mat.supr-con↗

arXiv2026

Nonreciprocal Quantum Mpemba Effect

We demonstrate a nonreciprocal quantum Mpemba effect. Consider a broad class of open quantum systems, each coupled to two isomorphic reservoirs through symmetric ports. Interchanging the parameters of the two reservoirs -- a discrete operation we call the swap -- turns the quantum Mpemba effect on or off without changing the initial states. The swap modifies the Liouvillian, yet a structural symmetry pins the eigenvalues while rotating only the eigenvectors. The nonreciprocity therefore leaves no trace in the spectrum and is carried entirely by the eigenvectors. Concretely, the swap alters the far state's projection onto the slowest mode, switching whether it bypasses the slowest relaxation channel. At a Liouvillian exceptional point, the far state's relaxation switches from bypassing the slowest mode to avoiding the critical slowing, with the on--off contrast intact. There the spectrum-independent mechanism takes its purest form.

quant-ph↗

arXiv2026

Pressure-induced Structural Phase Transition, Metallization, and Superconductivity in layered metalloid dichalcogenide 1T-SiTe$_2$

Layered transition-metal dichalcogenides (TMDs) have attracted considerable attention as promising platforms for exploring emergent physics and potential device applications. In contrast, metalloid-based dichalcogenide counterparts remain largely underexplored. Here, we report the pressure-induced structural phase transition, metallization, and superconductivity in the layered metalloid dichalcogenide 1T-SiTe$_2$. At ambient pressure, 1T-SiTe$_2$ crystallizes in a trigonal crystal structure (space group: $P\bar{3}m1$) and exhibits intrinsic semiconducting transport characteristics. Upon pressurization, in concomitant with the suppression of semiconducting behavior in resistance, superconductivity emerges at around 6.7 GPa. The superconducting transition temperature (T$_c$) rises continuously with increasing pressure and finally saturates at approximately 5.5 K for pressures above 30 GPa. During the compression, 1T-SiTe$_2$ experiences three structural phase transitions, and the phase transition pressures are highly consistent with the anomalous transport responses observed experimentally, indicating that the changes of transport behavior of 1T-SiTe$_2$ under pressure are structurally-driven. Our work extends TMD superconductors into the realm of metalloid systems and provides a new platform for exploring novel physics in quasi two-dimensional materials without transition-metal elements.

cond-mat.supr-con↗

arXiv2026

Interlayer electronic coherence links magnetism and superconductivity in Ruddlesden-Popper nickelates

The extent to which electronic dimensionality influences magnetism and superconductivity in Ruddlesden-Popper (RP) nickelates remains unsettled. Here we report high-precision crystallographic-axis-resolved dc transport measurements on high-quality single crystals of bilayer and trilayer RP nickelates. Using a six-terminal geometry, we self-consistently determine the intrinsic in-plane ($ρ_\parallel$) and out-of-plane ($ρ_\bot$) resistivities on the same crystal, while minimizing uncertainties associated with current redistribution in highly anisotropic conductors. We uncover strong intrinsic electronic anisotropy in both bilayer and trilayer nickelates, in contrast to the weak anisotropy inferred from conventional four-probe measurements. Moreover, $ρ_\bot$ exhibits a nonmonotonic temperature dependence, revealing a universal coherent-to-incoherent crossover in interlayer transport. Across the RP nickelate series, the maximum superconducting transition temperature ($T_c$) observed under pressure is inversely correlated with the ambient-pressure resistivity anisotropy, suggesting that stronger interlayer electronic coherence is favorable for superconductivity. In addition, $ρ_\bot$ serves as an exceptionally sensitive and selective probe of magnetic and density-wave orders, exhibiting pronounced anomalies, whereas only weak signatures are observed in $ρ_\parallel$. Our results highlight interlayer coherence as a key organizing parameter that both tracks the relevant magnetic correlations and is closely tied to superconductivity, providing stringent constraints on microscopic theories of high-$T_c$ superconductivity in nickelates.

cond-mat.str-el↗

arXiv2025

Enhanced superconductivity in the compressively strained bilayer nickelate thin films by pressure

The discovery of high temperature superconductivity in the nickelate system has stimulated enormous interest in the community of condensed matter physics. Recently, superconductivity with an onset transition temperature (Tc^onset) over 40 K was achieved in La3Ni2O7 and (La,Pr)3Ni2O7 thin films at ambient pressure due to in-plane compressive strain. This observation has sparked enormous attention because measurements on superconducting properties can be accessible with many commonly used experimental tools. On the other hand, the Tc in these thin films is much lower than that of the bulk bilayer nickelates under pressure. Here we report the enhancement of Tc^onset to over 60 K by applying hydrostatic pressure on the compressively strained superconducting bilayer nickelate thin films. The Tc^onset firstly ramps up with pressure, then it slightly drops down after reaching the maximum Tc^onset at about 61.5 K under a pressure of 9 GPa, showing a dome-like phase diagram. Hall effect measurements reveal that the dominant charge carriers are hole-like with a slight enhancement of charge carrier density with pressure in accompanying with the increase of Tc. Our theoretical results demonstrate that the enhancement of Tc arises from a cooperative amplification of magnetic fluctuations within and between the layers and increased metallicity under pressure. However, this enhancement exhibits saturation at higher pressures. These findings highlight the critical role of the interplay between interlayer and intralayer electronic correlations in bilayer nickelate superconductors and point to the potential of tuning Tc through controlled manipulation of the electronic structure and interactions.

cond-mat.supr-con↗

arXiv2024

Qubit coupled with an effective negative-absolute-temperature bath in off-resonant collision model

Quantum collision model provides a promising tool for investigating system-bath dynamics. Most of the studies on quantum collision models work in the resonant regime. In quantum dynamics, the off-resonant interaction often brings in exciting ffects. It is thereby attractive to investigate quantum collision models in the off-resonant regime. On the other hand, a bath with a negative absolute temperature is anticipated to be instrumental in developing thermal devices. The design of an effective bath with negative absolute temperature coupled to a qubit is significant for developing such thermal devices. We establish an effective negative-absolute-temperature bath coupled to a qubit with a quantum collision model in a far-off-resonant regime. We conduct a detailed and systematic investigation on the off-resonant collision model. There is an additional constraint on the collision duration resulting from the far-off resonant collision. The dynamics of the collision model in the far-off-resonant regime are different from the one beyond the far-off-resonant regime. Numerical simulations confirm the validity of the proposed approach.

quant-ph↗

arXiv2024

Unconventional superconductivity emerging along with the strange-metal behavior in UAs2 under pressure

The recently discovered spin-triplet superconductor candidate UTe2 with Tc = 2 K has attracted enormous attention because it possesses many interesting properties, such as the extremely high upper critical field Hc2(0), chiral superconductivity and spontaneous time-reversal symmetry breaking, etc., all these suggest that it may be the long-sought spin-triplet superconductor. Here we report the discovery of superconductivity up to Tc = 4K in one of its siblings, i.e., UAs2 under high pressures. Interestingly, the UAs2 shows metallic behavior with an antiferromagnetic (AFM) transition at about 274 K under ambient pressure. Upon applying pressure, this transition is pushed down to lower temperatures with improved electric conductivity. When the pressure rises to about 20-22 GPa, superconductivity occurs together with the emergence of a linear temperature dependence of normal state resistance, the latter is a hallmark of the strange-metal state. The superconductivity with the highest Tc = 4 K is reached under a pressure of about 26.8 GPa, and it is robust against magnetic field with the upper critical field μ0Hc2(0) ~ 12 T, far beyond the Pauli limit. Higher pressures will suppress the superconductivity and bring back the Fermi liquid behavior, showing a clear signature of quantum criticality. Our results open a new avenue for investigating the unconventional superconductivity concerning the mysterious 5f-band electrons in this uranium-based system.

cond-mat.supr-con↗

arXiv2024

Superconductivity up to 14.2 K in MnB$_4$ under pressure

The discovery of superconductivity in 3$d$-transition metal compounds with strong magnetism is interesting but rare. Especially for Mn-based compounds, there exist only very limited materials that show superconductivity. Here, we report the discovery of superconductivity up to 14.2 K in a Mn-based material MnB$_4$. By applying high pressures, we found the continuous suppression of a weak insulating behavior and the occurrence of superconductivity after about 30 GPa. With further increasing pressure, $T_\text{c}$ is gradually enhanced and reaches the maximum value of about 14.2 K at 150 GPa with a Fermi-Liquid behavior in the normal states. The synchrotron X-ray diffraction data reveal the unchanged monoclinic (S.G: $P2_1/c$) symmetry but an unusual crossover of the lattice parameters $b$ and $c$. Theoretical calculations based on the electron-phonon coupling picture reveal a very low $T_\text{c}$ (less than 1 K), manifesting an exotic pairing mechanism beyond the Bardeen-Cooper-Schrieffer (BCS) theory. Our findings show a promising way to explore high $T_\text{c}$ superconductivity by combining the 3d-transition metal magnetic elements and light elements.

cond-mat.supr-con↗

arXiv2024

A Unified Intracellular pH Landscape with SITE-pHorin: a Quantum-Entanglement-Enhanced pH Probe

An accurate map of intracellular organelle pH is crucial for comprehending cellular metabolism and organellar functions. However, a unified intracellular pH spectrum using a single probe is still lack. Here, we developed a novel quantum entanglement-enhanced pH-sensitive probe called SITE-pHorin, which featured a wide pH-sensitive range and ratiometric quantitative measurement capabilities. Subsequently, we measured the pH of various organelles and their sub-compartments, including mitochondrial sub-spaces, Golgi stacks, endoplasmic reticulum, lysosomes, peroxisomes, and endosomes in COS-7 cells. For the long-standing debate on mitochondrial compartments pH, we measured the pH of mitochondrial cristae as 6.60 \pm 0.40, the pH of mitochondrial intermembrane space as 6.95 \pm 0.30, and two populations of mitochondrial matrix pH at approximately 7.20 \pm 0.27 and 7.50 \pm 0.16, respectively. Notably, the lysosome pH exhibited a single, narrow Gaussian distribution centered at 4.79 \pm 0.17. Furthermore, quantum chemistry computations revealed that both the deprotonation of the residue Y182 and the discrete curvature of deformed benzene ring in chromophore are both necessary for the quantum entanglement mechanism of SITE-pHorin. Intriguingly, our findings reveal an accurate pH gradient (0.6-0.9 pH unit) between mitochondrial cristae and matrix, suggesting prior knowledge about ΔpH (0.4-0.6) and mitochondrial proton motive force (pmf) are underestimated.

q-bio.QM↗

arXiv2024

Record high superconducting transition temperature in Ti$_{1-x}$Mn$_x$ alloy with rich magnetic element Mn

It is well-known that magnetic moments are very harmful to superconductivity. A typical example is the element Mn whose compounds usually exhibit strong magnetism. Thus, it is very hard to achieve superconductivity in materials containing Mn. Here, we report enhanced superconductivity with the superconducting transition temperature ($T_\text{c}$) up to a record high-value of about 26 K in a beta-phase Ti$_{1-x}$Mn$_x$ alloy containing rich magnetic element Mn under high pressures. This is contrary to the intuition that the magnetic moments always suppress superconductivity. Under high pressures, we also found that in the middle-pressure regime, the Pauli limit of the upper critical field is surpassed. The synchrotron X-ray diffraction data shows an unchanged beta-phase with a continuous contraction of the cell volume, which is well supported by the first-principles calculations. Although the theoretical results based on electron-phonon coupling (EPC) can interpret the $T_\text{c}$ value in a certain pressure region, the monotonic enhancement of superconductivity by pressure cannot seek support from the theory. Our results show a surprising enhancement of superconductivity in Ti$_{1-x}$Mn$_x$ alloy with a considerable Mn content.

cond-mat.supr-con↗

arXiv2024

Evidence of genuine quantum effects in nonequilibrium entropy production

Entropy production is a fundamental concept that plays a crucial role in the second law of thermodynamics and the measure of irreversibility. It imposes rigorous constraints on the kinds of transformations allowed in thermodynamic processes. Using an optical setup, here we experimentally demonstrate the division of entropy production of an open quantum system into a population-related component and a coherence-related component, validating previous theoretical predictions. The coherence-related component represents a genuine quantum contribution with no classical counterpart. By adjusting bath temperatures and initial coherences of the system, we first derive the total entropy production due to both populations and coherences, then remove all the coherences of the system to solely obtain the population-related contribution. The difference between these two results permits to isolate the coherence-related term. Based on this division, our experiment ultimately proves that irreversibility at the quantum level can be reduced through properly harnessing the two contributions to entropy production.

quant-ph↗

arXiv2023

Signature of superconductivity in pressurized La$_4$Ni$_3$O$_{10}$

The discovery of high-temperature superconductivity near 80 K in bilayer nickelate La$_3$Ni$_2$O$_7$ under high pressures has renewed the exploration of superconducting nickelate in bulk materials. The extension of superconductivity in other nickelates in a broader family is also essential. Here, we report the experimental observation of superconducting signature in trilayer nickelate La$_4$Ni$_3$O$_{10}$ under high pressures. By using a modified sol-gel method and post-annealing treatment under high oxygen pressure, we successfully obtained polycrystalline La$_4$Ni$_3$O$_{10}$ samples with different transport behaviors at ambient pressure. Then we performed high-pressure electrical resistance measurements on these samples in a diamond-anvil-cell (DAC) apparatus. Surprisingly, the signature of possible superconducting transition with a maximum transition temperature ($T_\text{c}$) of about 20 K under high pressures is observed, as evidenced by a clear drop of resistance and the suppression of resistance drops under magnetic fields. Although the resistance drop is sample-dependent and relatively small, it appears in all of our measured samples. We argue that the observed superconducting signal is most likely to originate from the main phase of La$_4$Ni$_3$O$_{10}$. Our findings will motivate the exploration of superconductivity in a broader family of nickelates and shed light on the understanding of the underlying mechanisms of high-$T_\text{c}$ superconductivity in nickelates.

cond-mat.supr-con↗

arXiv2023

Temperature-related single-photon transport in waveguide QED

We propose a scheme to realize the single-photon transport affected by the temperature. The scheme is composed by a waveguide-atom interacting structure linked to a thermal bath. The single-photon reflection coefficient can be tuned by adjusting the temperature of the thermal bath. This provides a thermal control of the single-photon transport. Moreover, the temperature of the thermal bath can be estimated by measuring the single-photon transport. It is feasible that the estimation on the temperature is sensitive to slight changes of low temperature. This implies an avenue for implementing the optical thermometer with the ability to accurately measure the sample temperature in the low-temperature region.

quant-ph↗

arXiv2023

Absence of near-ambient superconductivity in LuH$_{2\pm\text{x}}$N$_y$

Recently near-ambient superconductivity was claimed in N-doped lutetium hydride (ref. 1). This induces a worldwide fanaticism about the dream of room temperature superconductivity under low pressures. By using a high pressure and high temperature synthesis technique, we have successfully obtained the nitrogen doped lutetium hydride (LuH$_{2\pm\text{x}}$N$_y$) with a dark-bluish color and a structure with the space group of $Fm\bar{3}m$ evidenced by x-ray diffraction. This structure is the same as that reported in ref. 1. The energy dispersive X-ray spectroscopy (EDS) confirmed the existence of nitrogen in some areas of the samples. At ambient pressure, we witness a kink of resistivity and magnetization at about 300 K, which may correspond to a rearrangement of hydrogen/nitrogen atoms, namely a structural transition. However, by applying a pressure from 1 GPa to 6 GPa, we have seen a progressively optimized metallic behavior without showing superconductivity down to 10 K. Temperature dependence of magnetization shows a roughly flat feature between 100 and 320 K, and the magnetization increases with magnetic field at 100 K, all these are not expected for superconductivity at 100 K. Thus, we conclude the absence of near-ambient superconductivity in this nitrogen-doped lutetium hydride under pressures below 6 GPa.

cond-mat.supr-con↗

arXiv2023

Pressure induced color change and evolution of metallic behavior in nitrogen-doped lutetium hydride

By applying pressures up to 42 GPa on the nitrogen-doped lutetium hydride (LuH$_{2\pm\text{x}}$N$_y$), we have found a gradual change of color from dark-blue to pink-violet in the pressure region of about 12 GPa to 21 GPa. The temperature dependence of resistivity under pressures up to 50.5 GPa shows progressively optimized metallic behavior with pressure. Interestingly, in the pressure region for the color change, a clear decrease of resistivity is observed with the increase of pressure, which is accompanied by a clear increase of the residual resistivity ratio (RRR). Fitting to the low temperature resistivity gives exponents of about 2, suggesting a Fermi liquid behavior in low temperature region. The general behavior in wide temperature region suggests that the electron-phonon scattering is still the dominant one. The magnetoresistance up to 9 tesla in the state under a pressure of 50.5 GPa shows an almost negligible effect, which suggests that the electric conduction in the pink-violet state is dominated by a single band. It is highly desired to have theoretical efforts in understanding the evolution of color and resistivity in this interesting system.

cond-mat.supr-con↗

arXiv2022

All-optical control of thermal conduction in waveguide QED

We investigate the heat conduction between two one-dimension waveguides intermediated by a Laser-driving atom. The Laser provides the optical control on the heat conduction. The tunable asymmetric conduction of the heat against the temperature gradient is realized. Assisted by the modulated Laser, the heat conduction from either waveguide to the other waveguide can be suppressed. Meanwhile, the conduction towards the direction opposite to the suppressed one is gained. The heat currents can be significantly amplified by the energy flow of the Laser. Moveover, the scheme can act like a heat engine.

quant-ph↗

arXiv2022

Supervised Learning by Chiral-Network-Based Photonic Quantum Computing

Benefiting from the excellent control of single photons realized by the emitter-photon-chiral couplings, we propose a novel potential photonic-quantum-computation scheme to perform the supervised learning tasks. The gates for photonic quantum computation are realized by properly designed atom-photon-chiral couplings. The quantum algorithm of supervised learning, composed by integrating the realized gates, is implemented by the tunable gate parameters. The learning ability is demonstrated by numerically simulating the performance of regression and classification tasks.

quant-ph↗

arXiv2022

Comparative studies on unconventional superconductivity in Cr$_3$Ru compounds with bcc and A15 structures

Chromium (Cr) is a transition metal element with 3$d$ orbital electrons. In most compounds containing Cr, due to the correlation effect, twofold features of localization and itinerancy are expected. The localization gives rise to a magnetic moment, while the latter exhibits as the effective coherent weight for conductivity. Here we report the physical properties of Cr$_3$Ru compounds with bcc or A15 phases by using multiple experimental tools. The resistivity measurements show sharp superconducting transitions at $T_{\rm c}$ = 2.77 K and $T_{\rm c}$ = 3.37 K for the bcc and A15 structures. A high residual resistivity exists for both samples with the mean-free-path about 2 nm. Magnetization measurements also show rather narrow transitions, with a clear hump structure at high temperatures around 150 K, which may be ascribed to the remaining antiferromagnetic spin fluctuations. The specific heat coefficient reveals a clear jump at $T_{\rm c}$. We find that s-wave gaps can be adopted to fit the low temperature specific heat data yielding ratios of about $2Δ/k_{\scriptscriptstyle B}T_{\rm c}$ $\approx$ 3.6, indicating a moderate pairing strength. Interestingly, the Wilson ratios are 3.81 and 3.62 for the bcc and A15 phases, suggesting a moderate correlation effect of conducting electron in the normal state. Besides, for samples with A15 structure, another specific heat anomaly occurs at about 0.85 K and is sensitive to magnetic fields. By applying high pressures, both system exhibit an enhancement of $T_{\rm c}$ with a rate of about 0.019 K/GPa and 0.013 K/GPa for the bcc and A15 phases. We also conduct tunneling spectrum measurements and found that the coherence peaks are strongly smeared out. The strong suppression to the coherence peaks may be ascribed to the strong scattering. Our combinatory results point to an unconventional superconductivity in these Cr based compounds.

cond-mat.supr-con↗