Entanglement and Bell’s inequality violation above room temperature in metal carboxylates

Abstract

In the present work we show that a special family of materials, the metal carboxylates, may have entangled states up to very high temperatures. From magnetic susceptibility measurements, we have estimated the critical temperature below which entanglement exists in the cooper carboxylate {Cu2(O2CH)4}{Cu(O2CH)2(2-methylpyridine)2}, and we have found this to be above room temperature (Te ∼ 630 K). Furthermore, the results show that the system remains maximally entangled until close to ∼ 100 K and the Bell's inequality is violated up to nearly room temperature (∼ 290 K).

Compostos magnéticos moleculares: o desenvolvimento de novos materiais magnéticos nanoestruturados

“…Algoritmos baseados nas propriedades do Mn12Ac já foram propostos, assim como a existência de estados quanticamente emaranhados. 101 Um grande esforço tem sido feito no desenvolvimento da tecnologia de manipulação de spins, como a técnica de ressonância paramagnética eletrônica pulsada, para aplicação futura em dispositivos para computação quântica. 4 …”

Carboxylate-based molecular magnet: One path toward achieving stable quantum correlations at room temperature

“…In spite of that, it is fragile and can easily vanish due to the inevitable interaction of the system with its environment [4]; and due to this condition, it was thought that entanglement could only exist at low temperatures. However, recently, it has been shown that entanglement can also exist at higher temperatures, and can be detected through the measurement of some thermodynamic observables [5][6][7][8][9][10][11][12][13][14][15][16][17].…”

“…They combine classical properties, found in any macroscopic magnet, with quantum ones, such as quantum interference and entanglement. The large gap between the ground state and the first-excited state found in some materials allows the existence of entangled quantum states at higher temperatures [6,11,13,17]. The study of molecular magnets opens thus doors for new research toward to the limits of quantum mechanics; and several aspects are worthy of a thorough research, such as (i) how robust their quantum features are against temperature and (ii) how large systems can support these properties.…”

“…In spite of that, it is fragile and can easily vanish due to the inevitable interaction of the system with its environment [4]; and due to this condition, it was thought that entanglement could only exist at low temperatures. However, recently, it has been shown that entanglement can also exist at higher temperatures, and can be detected through the measurement of some thermodynamic observables [5][6][7][8][9][10][11][12][13][14][15][16][17].Nevertheless, quantum entanglement does not encompass all quantum correlations in a system and recent studies have greatly expanded the notion of quantum correlations [18][19][20][21][22][23][24][25][26][27][28][29]; and the measure of quantum excess of correlations has been named as quantum discord [19][20][21]. In the last years, it was understood that quantum discord has an important role in many quantum information processing even without entanglement.…”

“…The quantum properties of several materials have been deeply analyzing by means of thermodynamic quantities [5][6][7][8][9][10][11][12][13][14][15][16][17], and magnetic susceptibility χ has been a good benchmark [5-8, 10-13, 17] due to the easy experimental access. For the material under consideration, the experimental χT quantity, for the whole range of temperature considered (<300 K), is smaller than the Curie constant of the dimer C = 1.34 × 10 −4 µ B K/FU-Oe; and it is a clear signature that at least one exchange interactions into the system is larger than the thermal energy at room temperature.…”