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Concatenating bosonic error-correcting codes with qubit codes can substantially boost the error correcting power of the original qubit codes. It is not clear how to concatenate optimally, given that there are several bosonic codes and concatenation schemes to choose from, including the recently discovered Gottesman-Kitaev-Preskill (GKP) – stabilizer codes [Phys. Rev. Lett. 125, 080503 (2020)] that allow protection of a logical bosonic mode from fluctuations of the conjugate variables of the mode. We develop efficient maximum-likelihood decoders for and analyze the performance of three different concatenations of codes taken from the following set: qubit stabilizer codes, analog or Gaussian stabilizer codes, GKP codes, and GKP-stabilizer codes. We benchmark decoder performance against additive Gaussian white noise, corroborating our numerics with analytical calculations. We observe that the concatenation involving GKP-stabilizer codes outperforms the more conventional concatenation of a qubit stabilizer code with a GKP code in some cases. We also propose a GKP-stabilizer code that suppresses fluctuations in both conjugate variables without extra quadrature squeezing and formulate qudit versions of GKP-stabilizer codes. 

MnCoGe-based materials have the potential to exhibit giant magnetocaloric effects due to coupling between magnetic ordering and a martensitic phase transition. Such coupling can be realized by matching the temperatures of the magnetic and structural phase transitions. To understand the site preference of different elements and the effect of hole or electron doping on the stability of different polymorphs of MnCoGe, crystal orbital Hamilton population (COHP) analysis has been employed for the first time to evaluate peculiarities of chemical bonding in this material. The shortest Mn–Mn bond in the structure is found to be pivotal to the observed ferromagnetic behavior and structural stability of hexagonal MnCoGe. Based on this insight, eliminating anti-bonding features of the shortest Mn-Mn bond at the Fermi energy is proposed as a feasible way to stabilize the hexagonal polymorph, which is then realized experimentally by substitution of Zn for Ge. The hexagonal MnCoGe structure is stabilized due to depopulation of the anti-bonding states and strengthening of the Mn–Mn bonding. This change in chemical bonding leads to anisotropic evolution of lattice parameters. The structural and magnetic properties of Zn-doped MnCoGe have been elucidated by synchrotron X-ray diffraction and magnetic measurements, respectively. 

Gadolinium silicide (Gd 5 Si 4 ) nanoparticles are an interesting class of materials due to their high magnetization, low Curie temperature, low toxicity in biological environments and their multifunctional properties. We report the magnetic and magnetothermal properties of gadolinium silicide (Gd 5 Si 4 ) nanoparticles prepared by surfactant-assisted ball milling of arc melted bulk ingots of the compound. Using different milling times and speeds, a wide range of crystallite sizes (13–43 nm) could be produced and a reduction in Curie temperature ( T C ) from 340 K to 317 K was achieved, making these nanoparticles suitable for self-controlled magnetic hyperthermia applications. The magnetothermal effect was measured in applied AC magnetic fields of amplitude 164–239 Oe and frequencies 163–519 kHz. All particles showed magnetic heating with a strong dependence of the specific absorption rate (SAR) on the average crystallite size. The highest SAR of 3.7 W g −1 was measured for 43 nm sized nanoparticles of Gd 5 Si 4 . The high SAR and low T C , (within the therapeutic range for magnetothermal therapy) makes the Gd 5 Si 4 behave like self-regulating heat switches that would be suitable for self-controlled magnetic hyperthermia applications after biocompatibility and cytotoxicity tests. 

Abstract A giant barocaloric effect (BCE) in a molecular material Fe₃(bntrz)₆(tcnset)₆(FBT) is reported, where bntrz = 4‐(benzyl)‐1,2,4‐triazole and tcnset = 1,1,3,3‐tetracyano‐2‐thioethylepropenide. The crystal structure of FBT contains a trinuclear transition metal complex that undergoes an abrupt spin‐state switching between the state in which all three Fe^IIcenters are in the high‐spin (S = 2) electronic configuration and the state in which all of them are in the low‐spin (S = 0) configuration. Despite the strongly cooperative nature of the spin transition, it proceeds with a negligible hysteresis and a large volumetric change, suggesting that FBT should be a good candidate for producing a large BCE. Powder X‐ray diffraction and calorimetry reveal that the material is highly susceptible to applied pressure, as the transition temperature spans the range from 318 at ambient pressure to 383 K at 2.6 kbar. Despite the large shift in the spin‐transition temperature, its nonhysteretic character is maintained under applied pressure. Such behavior leads to a remarkably large and reversible BCE, characterized by an isothermal entropy change of 120 J kg⁻¹K⁻¹and an adiabatic temperature change of 35 K, which are among the highest reversible values reported for any caloric material thus far.