We now know, however, that quantum entanglement is indeed real.
And if we could better understand it, Dr Mikkel Andersen said, the implications were potentially huge.
The discovery of quantum mechanics as the fundamental mechanical theory have already enabled inventions that revolutionised our society.
Among them have been the transistor, providing the enabling technology for computers and all digital data processing devices, and lasers, which allow the incredible rate of information transfer in optical fibres that power our modern broadband internet.
"Despite the enormous impact these and other quantum technologies have had on our lives the potential for far more powerful technologies is immense."
And, despite experiments indicating its exciting promise, no widespread technology today has yet made use of quantum entanglement.
One of the few examples on the horizon was the quantum computer.
While still under development, it stood to dramatically outperform today's computers – just one machine with less than 100 quantum bits could even beat the world's combined conventional computer power for certain calculations.
Scientists have thus been predicting the "second quantum revolution".
Why has it been so slow to emerge?
Andersen said quantum entanglement had proven to be a very fragile resource that was easily lost.
"In particular it is often kept only at ultra cold temperatures and any heating is detrimental," he said.
"To make widespread entanglement based technologies, it is therefore very important to make more robust sources of it, and this presently comprises a large international research trend."
In a new study, which recently received a $935,000 grant from the Marsden Fund, Andersen will seek to answer a single question: could heating, which usually destroyed quantum entanglement, actually generate it?
"If our idea to do this succeed, it will provide a robust route to entanglement generation for future technologies."
Powered by astounding progress in scientists' ability to control atoms, Andersen will assemble individual atomic pairs held by laser beams, and watch through a sensitive microscope as the atoms entangle when they collide.
If successful, the project would provide the world's smallest entanglement-enhanced device capable of detecting magnetic field variations on a nanometer scale.
"According to theory, this will cause a transfer of thermal energy from the motion of the atoms to their electronic states, in a way that leaves the electronic states entangled," Andersen said.
"We hope to provide a fundamentally new way to generate entanglement that is far more robust than the present.
"Moreover, we are aiming to show that the entanglement generated can be used to enhance the performance of magnetic field sensors beyond what is achievable today.
"This is important since not all entanglement is useful, so we would like to show that what we generate is."
Observing and understanding this phenomenon would help power future quantum technologies, enabling more secure communications, faster computations, and more precise measurements.
But Andersen stressed the study was one of fundamental research – and real-life applications that could stem from it weren't his team's key goal.
