Publications by authors named "Christian Arenz"

Single-qubit measurements are typically insufficient for inferring arbitrary quantum states of a multiqubit system. We show that, if the system can be fully controlled by driving a single qubit, then utilizing a local random pulse is almost always sufficient for complete quantum-state tomography. Experimental demonstrations of this principle are presented using a nitrogen-vacancy (NV) center in diamond coupled to a nuclear spin, which is not directly accessible.

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Future quantum devices often rely on favorable scaling with respect to the number of system components. To achieve desirable scaling, it is therefore crucial to implement unitary transformations in a time that scales at most polynomial in the number of qubits. We develop an upper bound for the minimum time required to implement a unitary transformation on a generic qubit network in which each of the qubits is subject to local time dependent controls.

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The aorta with its compliance plays a major role in hemodynamics as it saves a portion of ejected blood during systole which is then released in diastole. The aortic compliance decreases with increasing age, which is related to several cardiovascular imparities and diseases. Changes in flow patterns and pressure curves, due to varying aortic compliance, are difficult to investigate in vivo.

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