بررسی نقش برهم‌کنش ژیالوشینسکی-موریاو میدان مغناطیسی خارجی در افزایش استقامت درهم‌تنیدگی کوانتومی در مقابل افت و خیزهای گرمایی

در این مقاله یک سامانه دو اسپینی، با کمک الگوی آیزینگ و برهم‌کنش ژیالوشینسکی- موریا، در میدان های مغناطیسی خارجی مختلف بررسی شده است. با استفاده از تابع چگالی گرمایی، نقش دما بر درهم تنیدگی سامانه کوانتومی بررسی شد. معیار بررسی درهم تنیدگی تابع توافق در نظر گرفته شده است. تاثیر میدان مغناطیسی و برهم‌کنش ژیالوشینسکی- موریا در احیای درهم تنیدگی سامانه در دماهای بالا مورد مطالعه قرار گرفت. از آن جایی که میدان مغناطیسی در جهت جفت‌شدگی آیزینگ اسپینی در نظر گرفته شده بود، بنابراین تاثیر آن بر کاهش و حذف درهم‌تنیدگی در دماهای بالا چندان قابل توجه نبود. در مقابل، حضور برهم‌کنش dm و افزایش بزرگی آن، نقش مثبتی در حفظ درهم تنیدگی در دماهای بالا داشت. در دماهای نزدیک به صفر نیز حضور چشمگیر این برهم‌کنش در ایجاد درهم‌تنیدگی اولیه سامانه کوانتومی مشاهده می‌شود. بنابراین اگر در سامانه اسپینی، قدرت برهم‌کنش dm از مرتبه مناسبی در مقایسه با برهم‌کنش آیزینگ باشد، به خوبی می تواند اثرات اختلالی مغناطیسی خارجی را کاهش داده و همچنین درهم تنیدگی گرمایی سامانه را در برهم‌کنش با محیط تا حد خوبی حفظ نماید.

investigating the role of the dzyaloshinskii-moriya interaction and external magnetic field in increasing endurance against thermal fluctuations

1. introductionin this paper, a two-spin system, under the ising model and the dzyaloshinskii-moriya interaction, has been analyzed in different external magnetic fields. using the thermal density function, the role of temperature on the system’s entanglement was investigated. the criterion for examining the entanglement is the concurrence function. the effect of the magnetic field and the dzyaloshinskii-moriya interaction on the revival of the system’s entanglement at high temperatures was studied. since the magnetic field was considered in the direction of the spin ising coupling, its effect on reducing and eliminating entanglement at high temperatures was not very significant. in contrast, the presence of the dm interaction had a positive role in maintaining entanglement at high temperatures. at temperatures close to zero, the significant presence of this interaction in creating the initial entanglement of the quantum system is also observed. therefore, if in a spin system, the strength of the dm interaction is of a suitable order compared to the ising interaction, it can well reduce the effects of external magnetic perturbations and also maintain the thermal entanglement of the system in the interaction with the environment to a good extent. spin models such as the heisenberg model are ideal candidates for the generation, manipulation, and propagation of entangled states. spin systems are extensively used in quantum computing. other quantum systems, such as quantum dots, superconductors, optical lattices, and photons, can also be candidates for qubit selection for quantum entanglement applications. spin chains with different spin interaction models, such as the isotropic and anisotropic heisenberg models xxx, xxz, and xyz, have also been investigated as entangled systems, and the crucial role of these interactions in the generation, modification, and destruction of entanglement has been recognized. in addition to the heisenberg interactions, another type of interaction is observed in spin systems, which arises from the coupling of the electron spin with the nuclear angular momentum of the positive ion. this asymmetric spin exchange interaction is called the dzyaloshinskii-moriya interaction, abbreviated as the dm interaction, and has a significant impact on the physics of low-dimensional quantum magnets. research has shown that the dm interaction can affect the dynamic behavior of the entangled system and even play a role in causing or preventing entanglement sudden death (esd) in some cases. the dm interaction also plays a prominent role in weak ferromagnetism and weak antiferromagnetism systems with weak symmetry. 2. methodologythe interactions between particles of a spin system undergo constructive or destructive changes when interacting with the environment. maintaining entanglement between qubits in these interactions is very important, especially for applications such as quantum communications and quantum computing, and determines the efficiency of these technologies. in this paper, a two-spin system with ising and dm interactions is considered. an external magnetic field is applied to this system, and its effect on the thermal entanglement of the system is investigated. it is expected that by examining the temperature changes of the entangled states, a better understanding of why this change occurs can be achieved. by analyzing the results of the effect of different interactions at temperatures above zero, appropriate methods can be proposed to maintain the system's entanglement in the face of environmental effects. the ising function, since it only creates a phase difference in adjacent spins, cannot lead to entanglement in quantum systems by itself. on the contrary, the dm interaction is inherently entanglement-generating because it creates a coupling between spin and orbit, leading to nonlinear spin interactions. the dm interaction term is asymmetric and can induce significant quantum correlations between spins. the dm interaction is significant in spin systems with broken inversion symmetry, such as chiral magnets and topological insulators. it can also be exploited to design entangled gates in quantum computing architectures involving spin systems. for this reason, the dm interaction can be a testbed for studying the generation and dynamics of entanglement in condensed matter systems. temperature plays an important role in quantum entanglement, especially in physical systems that are always operated at temperatures above zero kelvin. at temperatures above zero, quantum systems interact with their environment, which leads to thermal noise. this noise tends to reduce quantum correlations such as entanglement. in fact, at higher temperatures, the specific quantum superpositions of spin states required for entanglement become a statistical state, disrupting the system's entanglement. the study of the effect of dm interaction on the system's entanglement at different temperatures indicates the positive role of this interaction. at temperatures close to zero, the significant presence of this interaction in creating the initial entanglement of the quantum system is also observed; therefore, if the strength of dm interaction in the spin system is of the appropriate order compared to the ising interaction, it can well reduce the effects of external magnetic disturbance caused by the environment and also maintain the thermal entanglement of the system in the interaction with the environment to a good extent. this result is important in that it highlights the role of choosing the appropriate material for sending entangled information by quantum systems and brings the practical applications of quantum entangled systems closer to ideal conditions. 3. conclusionin conclusion, in this paper, a two-spin system, with spin 2/1, under the ising model and the dzyaloshinskii-moriya interaction, dm, is analyzed in different external magnetic fields. the entanglement of the system was studied under thermal conditions and using the agreement function. the role of the magnetic field at different values of the dm interactions was investigated. since the magnetic field was considered in the direction of the spin ising coupling, its effect on the reduction and elimination of entanglement at high temperatures was not very significant. in contrast, the presence of the dm interaction and its increase in magnitude had a positive role in maintaining entanglement at high temperatures.