"This cover represents the novel quantum metal–organic framework (quMOF), {[(Gd)₃(mCB-L)₄(NO₃)(DMF)_x]_n·Solv}, constructed with a carborane linker and gadolinium (Gd) (III) ions at three distinct coordination sites. This quMOF constitutes a record-breaking 512-level qudit, capable of encoding up to 9 qubits—a major milestone for scalable Quantum Computing.", explains Elena Bartolomé, first and co-corresponding author of this paper.

But, what are quMOF's, and what are they used for?

"Now, quMOFs are a subclass of MOFs that incorporate arrays of spin “qubits” (quantum bits) within their structure. These qubits can be located at the metal nodes, along the linkers, or even inside the pores" explains Bartolomé. And adds: "quMOFs offer a promising pathway toward scalable quantum computing, as they enable the precise organization of identical two-level qubits—or even multi-level systems known as “qudits”—with strict control over their spatial separation and dilution, which is crucial to reduce quantum decoherence". 

Beyond quantum computation, quMOFs are also being explored for quantum sensing applications. For example, “quantum noses” (quNoses) can detect and distinguish between different molecules or gases by sensing changes in the quantum state of embedded spins.

How are quMOFS synthesized?

The MOF described in this work was synthesized through a chemical one-pot method, previously applied to other multivariate lanthanide-based MOFs. The researchers used a carborane-based organic linker, known for forming stable and versatile frameworks, and combined it with Gd(III) salts in solution. To investigate quantum properties, they also prepared magnetically diluted analogues by mixing Gd(III) and Y(III) in precise ratios. The resulting materials are crystalline, air-stable, and suitable for magnetic and quantum characterization. 

Cover published in ACS Applied Materials & Interfaces

 Why is this study relevant?

Quantum Computing has emerged as a revolutionary quantum technology with the potential to transform fields such as AI, data analysis, and optimization by solving problems beyond the reach of classical computers. Among the many platforms being explored, molecular spin qubits offer key advantages: they are inherently quantum, chemically tunable, identical, and can be produced through bottom-up synthesis.

"A key challenge, however, is scalability — increasing the number of quantum states to boost computing power and enable more complex algorithms. Our work addresses this challenge directly." explains Bartolomé. In the study presented, researchers introduce a novel carborane-based quMOF featuring three distinct Gd(III) sites, yielding an unprecedented d = (2S + 1)³ = 512-level qudit capable of encoding up to 9 qubits.

Which other relevant properties does this quMOF have?

Researchers performed an in-depth characterization of the Gd₃ quMOF’s magneto-thermal properties using dc/ac magnetometry, heat capacity measurements, and X-ray Magnetic Circular Dichroism (XMCD) at ALBA synchrotron. Its quantum potential was demonstrated through ab initio calculations and pulsed EPR experiments on magnetically diluted GdY analogues, revealing a phase memory time T_m = 0.7 µs and robust Rabi oscillations persisting up to 50 K.

"Beyond quantum computing, this Gd₃ MOF exhibits magnetocaloric effect (MCE), expanding its potential for cryogenic magnetic refrigeration. Leveraging this property, along with the carborane linkers’ ability to coordinate multiple lanthanides, they have recently developed multifunctional, self-refrigerated GdLn MOFs (Ln = Dy, Tb, Eu). Moreover, the magnetic properties of the Gd₃ MOF remain stable upon surface deposition, as shown by XAS-XMCD, making this system interesting for device integration and on-chip cooling applications." adds Bartolomé. 

This highly multidisciplinary study was made possible thanks to the close and long-standing collaboration between rearchers at ICMAB-CSIC, led by Elena Bartolomé and José Giner Planas, from the LMI group, and their colleagues at INMA-CSIC in Zaragoza. This work is part of the ICMAB-CSIC Severo Ochoa Programme, Materials for Electronics research line (CEX2023-001263-S).

Abstract

Metal–organic frameworks (MOFs) incorporating arrays of molecular spin qubits (quMOFs) offer a promising pathway toward scalable quantum computing. In this work, we introduce a novel quMOF, {[(Gd)₃(mCB-L)₄(NO₃)(DMF)_x]_n·Solv}, constructed with a carborane linker and Gd(III) ions at three distinct coordination sites.

We thoroughly characterize its magneto-thermal properties using dc/ac magnetometry, X-ray absorption spectroscopy, X-ray magnetic circular dichroism, and heat capacity measurements. The quantum computing potential is demonstrated through ab initio calculations and pulsed electron paramagnetic resonance on GdY-diluted analogues, revealing T_m= 0.7 μs and Rabi oscillations persisting up to 50 K. Each of the three isolated Gd(i) sites in GdY-MOFs functions as an 8-level qudit, accessible via X-band transitions. Notably, the triple-site Gd₃ quMOF provides an unprecedented qudit with d = (2S + 1)³ = 512 states, capable of encoding up to 9 qubits, marking a significant advance in the scalability of molecular-based quantum computing systems.

Reference

A Triple-Site Gd₃ Carborane Metal–Organic Framework toward Scalable Quantum Computing
Elena Bartolomé*, Xao-Bao Li, Ana Arauzo, Javier Luzón, Inés García-Rubio, José Giner Planas*
ACS Appl. Mater. Interfaces 2025, 17, 42082−42095
DOI: 10.1021/acsami.5c06002

About the cover

A novel carborane-based MOF featuring three distinct Gd(III) sites yields a record 512 level qudit capable of encoding 9 qubits, marking a major advance in the scalability of quantum computing. Pulsed EPR on GdY analogues reveals Tₘ = 0.7 μs at 3.6 K and Rabi oscillations persisting up to 50 K.

You can see and download the cover here.