Crank arrangement for driving a mechanical oscillator

Crank arrangement (1) for driving a pin-driven two degrees? of freedom mechanical oscillator (5), comprising:- a crank element (7) arranged to be rotationally driven about an axis of rotation (19) by means of a mechanical source of energy (M),- a crank slot (8) provided in said crank element, said crank slot being adapted to receive a driving pin (3) arranged to cause an inertial mass (5a) of said oscillator (5) to oscillate in response to rotation of said crank element (7),wherein said crank slot (8) comprises a driving section at least partially delimited by a drive surface (8a) and by a guiding surface (8c) situated opposite at least part of said driving surface (8a), said drive surface (8a) being arranged to drive said pin (3) in response to rotation of said crank element (7);characterised in that said crank slot (8) further comprises a return section adjoining said driving section, said return section being delimited by:- a braking surface (8d) adjoining said driving surface (8a) so as to form an obtuse interior angle (180°-a) therewith,- a return surface (8e) arranged opposite said braking surface (8d) at an acute angle (β) with respect thereto,wherein said crank slot (8) is configured such that said axis of rotation (19) is situated in said return section at a distance of less than one radius (Rp) of said drive pin (3) from said braking surface (8d).

Ultra-coherent nano-mechanical resonators for quantum optomechanics at room temperature

Amir Hossein Ghadimi

Mechanical oscillators are among the most important scientific tools in the modern physics. From the pioneering experiments in 18th by founding fathers of modern physics such as Newton, Hooke and Cavendish to the ground braking experiments in the 21th century where the merge of two massive black holes 1.3 billion light-year away detected on earth by a gravitational wave detectors, the high Q mechanical oscillators were at the core of many monumental experiments in physics. Their ability to couple to many different physical quantities such as mass, charge, acceleration, electro-magnetic forces and optical fields makes them an ideal candidate for sensing applications. In addition, their intrinsically low dissipation rates (¿m) results in reduced coupling to the thermal bath. Since the invention of micro/nano-technology in the second half of the 20th century and ability to control the dimensions at micro and nano-scales, new horizon was opened up for mirco/nanomechanical oscillators. Miniaturization of the mechanical oscillators made them small and stiff enough to be used in our handheld electronics where dozens of mechanical sensors such as accelerometers and gyroscopes are used in our laptops and smartphones everyday. Besides these technological advancements, since the beginning of 21th century, a new opportunity for mechanical oscillators emerged: the idea of ¿putting mechanics into quantum mechanics¿ and observing the quantum effects of these massive classical oscillators. Aside from the numerous technical challenges for achieving this goal, two fundamental obstacles has to solved: I) Even the smallest nano-mechanical oscillators still consist of billions of atoms and molecules and are orders of magnitude more massive that the traditional ¿quantum objects¿ such as atoms and molecules. Larger mass results in smaller zero point motion¿the length scale where quantum effects are visible¿which means in order to ¿see¿ these quantum effects, we have to detect smaller displacement than ever before. II) The second challenge is the low frequency of the mechanical oscillators which makes their thermal Brownian energy, orders of magnitude larger than the quantum ground state of the oscillator¿the energy scale where the quantum effects are visible¿as n_th = kBT/h¿>>1 even for a ¿/2¿ ~ 1GHz oscillator at room temperature. Both of these obstacles, can be seen as the competition between few fundamental rates: thermal decoherence and measurement rate/mechanical frequency. Thermal decoherence is the rate at which the mechanical oscillator exchange phonons ¿ quanta of mechanical energy (h¿)¿ with its thermal environment and is given by ¿decoherence = ¯ n_th*¿m. The first obstacle translates to having the measurement rate being faster than the decoherence rate of the mechanical oscillator, ¿measurement>¿decoherence. This means in order to see the quantum coherent motion of the mechanical oscillator, we have to ¿look¿ at it before it has time to exchange random thermal energy with its environment. In other words, the life time of the quantum states of macroscopic objects are limited by their thermal decoherence rate and we have to interact with the oscillator in this short lifetime. The second obstacle on the other hand, reduces to having the mechanical frequency larger than its thermal decoherence rate, ¿m >¿decoherence. Over the past 15 years, the field of cavity opto-mechanics was very successful in improving the measurement schemes and designing ...

EPFL2018

Mechanical oscillator with tunable isochronism defect

Simon Nessim Henein, Mohammad Hussein Kahrobaiyan, Mohamed Gamal Abdelrahman Ahmed Zanaty

Mechanical oscillator (1) for a timepiece comprising an inertial mass (3) arranged to oscillate about a neutral position under the effect of a restoring force provided by at least one elastic element (5),characterised in that said mechanical oscillator (1) further comprises a compensation spring (11) pivotably linked to said inertial mass (3) by means of a substantially rigid first connecting bar (15), said compensation spring (11) and said first connecting bar (15) being arranged so as to apply a compensating force to said inertial mass (3) which varies in function of displacement of said inertial mass (3) from its neutral position.This arrangement permits tuning of the isochronism and thus reduction and/or elimination of the isochronism defect of the oscillator typically caused by nonliearity of the restoring force provided by the elastic element (55)

2020

Two degree of freedom oscillator system

Simon Nessim Henein, Mohammad Hussein Kahrobaiyan, Billy Nussbaumer

Oscillator system (1) comprising:- a substantially planar frame (3);- a first sub-oscillator (5), a second sub-oscillator (7), a third sub-oscillator (9), and a fourth sub-oscillator (11), each sub-oscillator (5, 7, 9, 11) comprising a substantially rigid support (5a, 7a, 9a, 11a) carrying at least one inertial mass (5f, 5g, 7f, 7g, 9f, 9g, 11f, 11g) and being joined to said frame (3) by means of a respective flexure pivot (5b, 7b, 9b, 11b) defining a corresponding axis of rotation (5c, 7c, 9c, 11c), wherein:- the first sub-oscillator (5) is coupled to the second sub-oscillator (7) by means of a first coupler link (17), these sub-oscillators (5, 7) and said first coupler link (17) being arranged such that these sub-oscillators (5, 7) are constrained to rotate synchronously in opposite directions of rotation as said first coupler link (17) translates along a first axis of translation (17t);- the third sub-oscillator (9) is coupled to the fourth sub-oscillator (11) by means of a second coupler link (19), these sub-oscillators (9, 11) and said second coupler link (19) being arranged such that these sub-oscillators (9, 11) are constrained to rotate synchronously in opposite directions of rotation as said second coupler link (19) translates along a second axis of translation (19t) which is substantially orthogonal to said first axis of translation (17t);- said oscillator system (1) further comprises a driving block (25) arranged to be driven in a circular or oval pathway by means of a crank, said driving block (25) being coupled to said first coupler link (17) by means of a third coupler link (21) and to said second coupler link (19) by means of a fourth coupler link (27);and wherein said frame (3), said substantially rigid supports (5a, 7a, 9a, 11a), said flexure pivots (5b, 7b, 9b, 11b) and said coupler links (17, 19, 21, 27) are coplanar.

2020

Ultra-coherent nano-mechanical resonators for quantum optomechanics at room temperature

Amir Hossein Ghadimi

EPFL2018